How can I retrieve supplier RFC for Mexican reports?

The supplier site tax registration must match with the tax regime of the transaction to retrieve the supplier RFC for Mexican reports.

If the supplier site tax registration doesn't match, the default supplier site tax registration is used as RFC. If there's no supplier site tax registration, the supplier profile tax registration that matches the tax regime of the transaction is used as RFC. If there's no match, the default supplier profile tax registration will be used as RFC.