A manifold user can link their account to wagerwith.me by pasting their manifold markets API key (obtained from the profile page) in the wagerwith.me settings.

Currently, the only incentive to do this is to enable creating wagers on wagerwith.me that are automatically backed by a manifold market. Manifold is working on something similar: https://github.com/manifoldmarkets/manifold/pull/679

I will resolve this market by querying the number of distinct API keys that wagerwith.me has received at the end of the year. I promise to do my best to discount the effects of any sort of sybil attack aimed at influencing this market. Currently, the value is 2.