Ask HN: How to find a co-founder that would help you sell your product?

Well, we developed very cool app (both android and IOS) to help restaurants to speed up sales. Apparently it is not a very hot field to be in at this point, but we do have very unique product.

Myself is not a very good salesman, neither my partners, since we all come from a engineering background. We can do market research, manufacture hardware and build apps, but selling our product is hard.

Any suggestions?