Coterie Domain Resonance

Hello, I'm a very new ST and am running a session 0 tomorrow to set tone, coterie, city, stuff like that. I've got most of the rules down and memorized. The thing I'm having the most trouble with is the coterie sheet. Specifically Domain Resonance. I can't find anything in the books that tells me how to determine that.

Is that a player determined thing? Is it something I decide?

How do I determine that?

Thanks