Thomas —

You can't because, in many cases, excommunication is automatic (latae sententae) and in such cases, there is no formal record because there is no formal procedure. Only the person who commits the crime knows they are excommunicated.

If you only want a list of formal (ferendae sententae) excommunications done by the archbishop of San Francisco, I suggest writing the archdiocese and asking them.

Only they would have the records.

Eric