You'd be surprised how many poly folks there are in rural areas. You don't say which country or part of the country you are in, but if you can travel, there may just be poly groups close by that you could join and get to know a few people.
Try also the free dating site OKCupid - make sure you mention polyamory in your description and say that you are looking for friends. Quite a few poly folk use that site just to find other polys to be friends with.
Hope this helps!
Please check out The Birdcage - an open, friendly Polyamory forum for all parts of New York State
"Listen, or your tongue will make you deaf." - Native American Proverb