I ended up having to broach the subject via email with one of the LOR writers. She had offered to write a letter on the rotation, but I did not have the CV/ PS/ form/ ect. So I emailed her (with the CV, statement, and form attached) and recalled the conversation we had had. (it had been approx 9 mons prior) I asked her if she was still willing to write the letter and that my schedule was flexible if she would like to have a meeting.
I tried to catch her during office hours initially, but kept missing her, and it was getting close to September so.... not saying email is ideal, but it is not always as taboo as one would think. Actually, she told me she liked the convenience of having it on the computer where it was easier to keep it filed😎. But this was an attending who was not very formal, and who had already offered the letter.
Also, this was not the LOR from the PD or chair.