Here is the dialog containing the word. Is it a dialect?
A: まあ それじゃ一緒に食べない？
This is a colloquial form for 「する-か」． I don't think this is considered to be a particular dialect. (This form isn't used in western dialect, so it feels a bit eastern to my ear, just as the standard Japanese language does.)
In the dialog, A invites B to eat together, and B agrees (そうすっか == そうするか)． Other examples you might encounter is ~~でもすっか = でもするか.