You can use the Penalty Report or Scoring Inquiry.   Neither are particularly meant for T1, so might not be intuitive for the competitors.  You might need to help them with some language in the SI's and help from the race office.  

Could you use 'Standard Penalties' too?

'Standard Penalties' may be a way for the the officials to handle T1, but I do not see how the competitors could use to report/apply for a T1 penalty. Have I missed something?

We had the same non-intuitive confusion at both the 2021 and 2022 CORK events. Most of the time the boat had been protested by the R/C for touching a mark (arbitration cannot be applied because it is not a “protest by a boat” (T2).  At a pre-hearing boat/RC meeting (similar to a meeting to discuss what the R/C will testify at a OCS redress hearing) the boat realizes they want to accept a T1-Post Race Penalty and is forced to wade through both Penalty Report and Scoring Inquiry.

There are enough regattas that require on-water penalties to be reported after racing that “Penalty Report” is a clear description of the choice. “Scoring Inquiry” isn’t very close. A post race application for a Discretionary Penalty needs a P/C review to determine the penalty. Maybe both the DP and PRP needs another menu choice?

For the event I am involved in now our solution is to post this text on the online official notice board: 

Advice on taking penalty according to RRS T1

A competitor that wants to take a penalty according to RRS Appendix T1 (9.2 in Notice of Race) is advised to fill in "Penalty Report" available at the online notice board. In the "Penalty Report" form fill in "Penalty Taken" as "Scoring Penalty" and enter the text "T1" in the comment box to the right of "Scoring Penalty". Using this procedure to take the penalty according to RRS T1 will result in the smoothest administration.