Shannon,
Rives BFK is supposed to be buffered. If it is, it would not be suitable for cyanotype because the buffering agent would bleach the print. However, I have run pH tests on numerous batches of BFK and have yet to find any evidence of buffering. Also I have a number of cyanotype prints made on BFK which are 8-10 years old and look fine.
Nevertheless, BFK is a cold press paper and, while it is easy to coat well, you will not get fine detail with it. Actually, for some images, when you want a slightly impressionistic effect, it works well but, I would suggest that you try some other papers also. Especially try some hot press papers like Fabriano, for example. There are many others that will work. I have put cyanotype on almost everything including cloth (use natural fibers), wood, and handmade papers. In fact, that is the fun of these processes. Try different papers until you get the look you like.
Bob Schramm