I have a very dated page on pf at
http://home.nyc.rr.com/computertaijutsu/pf.html
At the end, in the odds and ends sections, I talk about it. Most of the detailed guides about ftp are all about using an ftp server, rather than a client. It can be confusing, because many of them don't really seem to specify that, they just talk about ftp. I think it was actually j65nk0 who straightened me out on this.