It's much harder to find local polyamorous or poly-friendly people to date in a small town. Polyamory is a new form of relationship, relatively speaking, and most people don't understand it.
You might have more luck telling people you do ethical non-monogamy. However, depending on your age, if you're in a conservative environment, most people are dating to find Mr or Ms Right, and expect to settle down, get married and have kids. They may think they can't do this with someone who is already married.
Do you have kids? Do you and your wife want kids?
Tips:
Join a dating site like Feeld and expect to have to travel to be able to date people in person who might share your mindset.
If you're pretty young, and most women near your age are husband-hunting and want kids of their own, consider dating older women who may be single, divorced, already have kids, have money of their own, and/or aren't looking to live together.
Are you open to having someone become a co-primary, or are you telling women you meet that they would have to be your secondary?
Check out our "Golden Nuggets" section. You will find articles, books, a podcast and former threads that discuss this (and many other common poly) topics.
Good luck!