How to add a custom attribute to a CMS message with Apple CMS services?

We would like to add an additional OID tag to the CMS signer info sequence using the Cryptographic Message Syntax Services library in macOS. We are able to generate a CMS message using the provided CMSEncoder* functions but are unable to insert the signing-certificate OID tag (1.2.840.113549.1.9.16.2.12) needed for conformance with the CAdES standard. Is there a way to insert a custom attribute into the signer sequence of a CMS message generated with Apple's CMS Services library?