https://www.bart.gov/siteinfo/contact
Renting from SFO is EASY. Not best airport layout due to ocean, but you take the SFO train to the Rental depot, get off and easy to find your rental. From there, exit right and head downtown (heading North).
Flown into and did a lot of business in San Fran and across into Oakland. Highly recommend BART unless you have family to visit and/ site see.
BART Station Maps
https://www.bart.gov/stations