Well, I'm an FFA, but even so I don't instantly like every BHM I see. In every case where I've fallen head-over-heels for some sexy (fat) guy, I fell in love with his personality first -- and after that point I found his body IRRESISTIBLE. (God, why are they always taken?!) So, my first piece of advice is to not solely focus on the feederism part of it, but to also talk about your other hobbies, interests, and just generally be a gentleman. Ideally, you should know it if you "click."

That being said, being an FFA is like being really bad at poker. I try to keep my sexual preference to myself (I'm just a private person), but I can't help but get weird, lusty looks on my face when big guys talk candidly about stuffing their faces, getting fatter, outgrowing clothing, or when they rub their bellies, eat with gusto, or just generally flaunt their gluttony about. Usually I start breathing faster, I might get flush, I'll look off to the side, try to avoid looking at their sexy bodies, and get a "far-off" look in my eyes as I try not to give away how turned on I am. So, if you do any of the above and see a woman acting like that, I think you've found a pretty good candidate for a (very shy) FFA.

If the FFA isn't shy, though, I think you'll know pretty much right away, and won't need any advice to recognize that she's into you. ;D

Good luck with your search!

I completely relate to all of this. It's exactly how I feel right now, unable to find a guy I like who isn't taken, and my friends who know just treat me like I'm the dorky weird one, or tell me my preference is "sweet," and laugh when I point to a sexy guy. Like their BDSM fetish is dangerous and cool and mine is endearingly innocent... People are jerks. It especially sucks when your friends are jerks.

I had a therapist for a year that I told almost everything, but I never told her about the fetish. Partly because I didn't think it mattered very much compared to the stuff that brought me there, and partly because I didn't want to have to spend a whole session explaining/defending it. She would always talk for half the session about herself anyway, so I had to pick my priorities...