The link below lists all SF municipal websites that provide public datasets related to property. I do not know if any of these datasets have ownership records.
I just found some more information from the city website sf311:
Assessor-Recorder - Owner of Property in San Francisco - 106765
Who is the owner of a property in San Francisco?
The San Francisco Assessor-Recorder's office maintains information on property ownership for properties located in San Francisco.
This information is not available online. You may get information by calling 554-5596 or by going to their office, Monday through Friday, between the hours of 8:00 a.m. – 5:00 p.m. They are located at City Hall, 1 Dr. Carlton B. Goodlett Place, Room 190, San Francisco, CA 94102.