Hi Peter,
It is quite possible that Rick's formal full-length concert for the Folklore Society of Greater Washington (D.C.), which I organized as FSGW's program chair, was recorded. That concert was the first (and perhaps only) time he did an FSGW concert. It was held at the Washington Ethical Society auditorium. Jennifer Woods (the keeper of the newsletter archive and the list of who has played when) could help pinpoint the date. Mudcatter Charlie Baum, who is currently on the board as a program organizer, could help find out if a tape was made, once we know the date. Since I don't live there anymore I can't do much more than point you in a direction, but if you want to PM me, Peter, I can give you Jennifer's contact info.
Kathy