Given that San Francisco is a city, it has rats.
San Francisco Dept of Public Health has a Rodent Abatement Program. They have lots of information about identifying and dealing with rodent problems, how to get help from the city for rodent problems, and info about the city's rodent abatement efforts.
If you need help with rats in your home, here are some exterminators.
If you would like rats as pets, here are some pet stores.
Also, Rat Girl is/was a thing.