Cal. Sts. & High. Code § 8041

Every protest shall contain a description of the property owned by each signer thereof, sufficient to identify the property, and if signed by more than one person, shall be accompanied by the affidavit of one of the signers that each signature thereto is the genuine signature of the person whose name purports to be thereto subscribed. If any signature is made by an agent, there shall be attached to the protest the affidavit of the agent that he is duly authorized to sign such protest. Any protest which does not comply with the foregoing requirements shall not be considered by the city council.