How do you tell if you have a dollar bill printed in San Francisco?

You don't have one.

US dollar bills are printed only in Washington DC and (since late 1990) in Fort Worth, Texas. Fort Worth bills have a little "FW" next to the plate number in the right-hand corner.

If you are asking about bills produced for the Federal Reserve Bank of San Francisco, $1 dollar bills, and older bills of higher denominations, have a large "L" within a circle to the left of the portrait. More current higher denomination bills have "L12" just beneath the left serial number (in type the same size as the serial number).