6-K - RADX - Equibles

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16 UNDER

THE SECURITIES EXCHANGE ACT OF 1934

For the Month of December 2025

Commission File Number: 001-41621

RADIOPHARM THERANOSTICS LIMITED

(Name of Registrant)

Level 3, 62 Lygon Street, Carlton South,Victoria, 3053, Australia

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F ☒ Form 40-F ☐

Indicate by check mark whether by furnishing the information contained in this Form, the registrant is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes ☐ No ☒

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): 82-

RADIOPHARM THERANOSTICS LIMITED

EXPLANATORY NOTE

Radiopharm Theranostics Limited (the “Company”) published three announcements (the “Public Notice”) to the Australian Securities Exchange on December 19, 2025 titled:

“Change of Director's Interest Notice (IT)”

“Change of Director's Interest Notice (PH)”

“Change of Director's Interest Notice (RC)”

A copy of the Public Notice is attached as an exhibit to this report on Form 6-K.

This report on Form 6-K (including the exhibit hereto) shall not be deemed to be “filed” for purposes of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) and shall not be incorporated by reference into any filing under the Securities Act of 1933, as amended, except as shall be expressly set forth by specific reference in such filing.

EXHIBITS

Exhibit <br><br>Number	Description
99.1	Change of Director's Interest Notice (IT)
99.2	Change of Director's Interest Notice (PH)
99.3	Change of Director's Interest Notice (RC)

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	RADIOPHARM THERANOSTICS LIMITED
Date: December 19, 2025	By:	/s/ Phillip Hains
		Phillip Hains
		Company Secretary

Exhibit 99.1

Appendix 3Y

Change of Director’s Interest Notice

Rule 3.19A.2

Appendix 3Y

Change of Director’s Interest Notice

Information or documents not available now must be given to ASX as soon as available. Information and documents given to ASX become ASX’s property and may be made public.

Introduced30/9/2001. Amended 01/01/11

Name of Entity:	Radiopharm Theranostics Limited (ASX: RAD)
ABN:	57 647 877 889

We (the entity) give ASX the following information under listing rule 3.19A.2 and as agent for the director for the purposes of section 205G of the Corporations Act.

Name of Director:	Ian Turner
Date of Last Notice:	30 May 2025

Part 1 - Changeof director’s relevant interests in securities

In the case of a trust, thisincludes interests in the trust made available by the responsible entity of the trust

Note: In the case of a company, interests which come within paragraph (i) of the definition of “notifiable interest of a director” should be disclosed in this part.

Direct or Indirect Interest	Direct and indirect
Nature of indirect interest<br><br> <br>(including registered holder)<br><br> <br>Note: Provide details of the circumstances<br> giving rise to the relevant interest.	Superannuation fund
Date of change	12 December 2025
No. of securities held prior to change			Shares	Options
****		Direct	2,530,595	18,167,928
****		Indirect	6,724,697	820,422
****		Total	9,255,292	18,988,350
Class	Unlisted Options
Numberacquired			Shares	Options
****		Direct	-	6,814,000
****		Indirect	-	-
****		Total	-	6,814,000
Number disposed			Shares	Options
****		Direct	-	-
****		Indirect	-	-
****		Total	-	-
Value/Consideration<br><br> <br>Note:<br><br> <br>If consideration is non-cash, provide details<br> and estimated valuation	Non-cash options issued, per resolution 8 approved by shareholders at the Annual General Meeting held on 20 November 2025
+ See chapter 19 for defined terms.
---	---
01/01/2011	Appendix 3Y Page 1

Appendix 3Y

Change of Director’s Interest Notice

No. of securities held after change			Shares	Options
****		Direct	2,530,595	24,981,928
****		Indirect	6,724,697	820,422
****		Total	9,255,292	25,802,350
Nature of change<br><br> <br>Example: <br><br>on-market trade, off-market trade, exercise of options, issue of securities under dividend reinvestment plan, participation in buy-back	Per resolution 8 approved by shareholders at the Annual General Meeting held on 20 November 2025

Part 2 –Change of director’s interests in contracts

Note: In the case ofa company, interests which come within paragraph (ii) of the definition of “notifiable interest of a director” should bedisclosed in this part.

Detail of contract	N/A
Nature of interest	N/A
Name of registered holder<br><br> <br>(if issued securities)	N/A
Date of change	N/A
No. and class of securities to which interest related prior to change<br><br> <br>Note: Details<br> are only required for a contract in relation to which the interest has changed	N/A
Interest acquired	N/A
Interest disposed	N/A
Value/Consideration<br><br> <br>Note: If consideration is non-cash, provide details<br> and an estimated valuation	N/A
Interest after change	N/A
+ See chapter 19 for defined terms.
---	---
Appendix 3Y Page 2	01/01/2011

Appendix 3Y

Change of Director’s Interest Notice

Part 3 – Closed period

Were the interests in the securities or contracts detailed above traded during a +closed period where prior written clearance was required?	No
If so, was prior written clearance provided to allow the trade to proceed during this period?	N/A
If prior written clearance was provided, on what date was this provided?	N/A
+ See chapter 19 for defined terms.
---	---
01/01/2011	Appendix 3Y Page 3

Exhibit 99.2

Appendix 3Y

Change of Director’s Interest Notice

Rule 3.19A.2

Appendix 3Y

Change of Director’s Interest Notice

Information or documents not available now must be given to ASX as soon as available. Information and documents given to ASX become ASX’s property and may be made public.

Introduced30/9/2001. Amended 01/01/11

Name ofEntity:	Radiopharm Theranostics Limited (ASX: RAD)
ABN:	57 647 877 889

We (the entity) give ASX the following information under listing rule 3.19A.2 and as agent for the director for the purposes of section 205G of the Corporations Act.

Name of Director:	Paul Hopper
Date of Last Notice:	18 December 2024

Part 1 - Changeof director’s relevant interests in securities

In the case of a trust, thisincludes interests in the trust made available by the responsible entity of the trust

Note: In the case of a company, interests which come within paragraph (i) of the definition of “notifiable interest of a director” should be disclosed in this part.

Direct or Indirect Interest	Direct
Nature of indirect interest<br><br> <br>(including registered holder)<br><br> <br>Note: Provide details of the circumstances<br> giving rise to the relevant interest.
Date of change	12 December 2025
No. of securities held prior to change			Shares	Options
****		Direct	53,900,000	35,500,000
****		Indirect	93,821,428	9,017,518
****		Total	147,721,428	44,517,518
Class	Unlisted options
Numberacquired			Shares	Options
****		Direct	-	18,142,000
****		Indirect	-	-
****		Total	-	18,142,000
Number disposed			Shares	Options
****		Direct	-	-
****		Indirect	-	-
****		Total	-	-
Value/Consideration<br><br> <br>Note:<br><br> <br>If consideration is non-cash, provide details<br> and estimated valuation	Non-cash options issued, per resolution 6 approved by shareholders<br>at the Annual General Meeting held on 20 November 2025
+ See chapter 19 for defined terms.
---	---
01/01/2011	Appendix 3Y Page 1

Appendix 3Y

Change of Director’s Interest Notice

No. of securities held after change			Shares	Options
****		Direct	53,900,000	53,642,000
****		Indirect	93,821,428	9,017,518
****		Total	147,721,428	62,659,518
Nature of change<br><br> <br>Example:<br><br> <br>on-market trade, off-market trade, exercise<br> of options, issue of securities under dividend reinvestment plan, participation in buy-back	Per resolution 6 approved by shareholders at the Annual General Meeting held on 20 November 2025

Part 2 –Change of director’s interests in contracts

Note: In the case of a company, interests which come within paragraph (ii) of the definition of “notifiable interest of a director” should be disclosed in this part.

Detail of contract	N/A
Nature of interest	N/A
Name of registered holder(ifissued securities)	N/A
Date of change	N/A
No. and class of securities to which interest related prior to change<br><br> <br>Note: Details<br> are only required for a contract in relation to which the interest has changed	N/A
Interest acquired	N/A
Interest disposed	N/A
Value/Consideration<br><br> <br>Note: If consideration is non-cash, provide details<br> and an estimated valuation	N/A
Interest after change	N/A
+ See chapter 19 for defined terms.
---	---
Appendix 3Y Page 2	01/01/2011

Appendix 3Y

Change of Director’s Interest Notice

Part 3 – Closed period

Were the interestsin the securities or contracts detailed above traded during a +closed period where prior written clearance was required?	No
If so, was prior written clearance provided to allow the trade to proceed during this period?	N/A
If prior written clearance was provided, on what date was this provided?	N/A

+ See chapter 19 for defined terms.
01/01/2011	Appendix 3Y Page 3

Exhibit 99.3

Appendix 3Y

Change of Director’s Interest Notice

Rule 3.19A.2

Appendix 3Y

Change of Director’s Interest Notice

Information or documents not available now must be given to ASX as soon as available. Information and documents given to ASX become ASX’s property and may be made public.

Introduced30/9/2001. Amended 01/01/11

Nameof Entity:	Radiopharm Theranostics Limited (ASX: RAD)
ABN:	57 647 877 889

We (the entity) give ASX the following information under listing rule 3.19A.2 and as agent for the director for the purposes of section 205G of the Corporations Act.

Name of Director:	Riccardo Canevari
Date of Last Notice:	3 November 2025

Part 1 - Changeof director’s relevant interests in securities

In the case of a trust, thisincludes interests in the trust made available by the responsible entity of the trust

Note: In the case of a company, interests which come within paragraph (i) of the definition of “notifiable interest of a director” should be disclosed in this part.

Direct or Indirect Interest	Direct
Nature of indirect interest<br><br> <br>(including registered holder)<br><br> <br>Note: Provide details of the circumstances<br> giving rise to the relevant interest.
Date of change	12 December 2025
No. of securities held prior to change			Shares	Options
****		Direct	20,029,986	110,949,299
****		Indirect	2,650,000	-
****		Total	22,679,986	110,949,299
Class	Unlisted Options
Numberacquired			Shares	Options
****		Direct	-	74,338,000
****		Indirect	-	-
****		Total	-	74,338,000
Number disposed			Shares	Options
****		Direct	-	-
****		Indirect	-	-
****		Total	-	-
Value/Consideration<br><br> <br>Note:<br><br> <br>If consideration is non-cash, provide details<br> and estimated valuation	Non-cash options issued, per<br>resolution 7 approved by shareholders at the Annual General Meeting held on 20 November 2025
+ See chapter 19 for defined terms.
---	---
01/01/2011	Appendix 3Y Page 1

Appendix 3Y

Change of Director’s Interest Notice

No. of securities held after change			Shares	Options
****		Direct	20,029,986	185,287,299
****		Indirect	2,650,000	-
****		Total	22,679,986	185,287,299
Nature of change<br><br> <br>Example:<br><br> <br>on-market trade, off-market trade, exercise<br> of options, issue of securities under dividend reinvestment plan, participation in buy-back	Per<br>resolution 7 approved by shareholders at the Annual General Meeting held on 20 November 2025

Part 2 –Change of director’s interests in contracts

Note: In the case of a company, interests which come within paragraph (ii) of the definition of “notifiable interest of a director” should be disclosed in this part.

Detail of contract	N/A
Nature of interest	N/A
Name of registered holder<br><br> <br>(if issued securities)	N/A
Date of change	N/A
No. and class of securities to which interest related prior to change<br><br> <br>Note: Details<br> are only required for a contract in relation to which the interest has changed	N/A
Interest acquired	N/A
Interest disposed	N/A
Value/Consideration<br><br> <br>Note: If consideration is non-cash, provide details<br> and an estimated valuation	N/A
Interest after change	N/A

+ See chapter 19 for defined terms.
Appendix 3Y Page 2	01/01/2011

Appendix 3Y

Change of Director’s Interest Notice

Part 3 – Closed period

Were the interestsin the securities or contracts detailed above traded during a +closed period where prior written clearance was required?	No
If so, was prior written clearance provided to allow the trade to proceed during this period?	N/A
If prior written clearance was provided, on what date was this provided?	N/A
+ See chapter 19 for defined terms.
---	---
01/01/2011	Appendix 3Y Page 3