Carlson Butcher Supply
From Burden's Landing
50 Mendell Street, #12
San Francisco, CA 94124
415-648-2601
According to the butcher at Bi-rite, they sell pink salt. According to this Chowhound post, they are open M-F, 7am-4pm.
Called them on January 18, 2012. Carl's Seasoning & Food seems to be a side business, open M-Th from 7:30-11am.