How about a Grocery Outlet on Geary at 27th/28th?
Actually, GO may be moving into the Geary/27th location.
This was from the SF Business Times in June 2011:
Grocery Outlet is growing quickly throughout Northern California, but is struggling to re-enter the San Francisco market. The third-generation Berkeley-based family business has been looking aggressively for the past couple of years for a San Francisco spot, and is close to signing its first lease in the Richmond district. The first San Francisco Grocery Outlet will likely open in the first half of 2012, and the city will be a multi-outlet market, said co-CEO MacGregor Read.
I don't know of any other vacant supermarkets in the Richmond District.