Re: When do you sign RN?
I think you about summed up the appropriate times. When you're working as a nurse or using your nursing education in some capacity, like serving in a nursing organization or publishing a journal article.
When I sign EMS run reports, I don't sign RN, because I'm operating as a medic and in my service the RN doesn't give me any sort of extra privileges or expanded scope of practice.
I've heard of people who have signed checks at the grocery store with RN, but I think usually it's accidental because they've been doing it at work all day, not because they're trying to flaunt the credentials.