Brokered practicums
The RTO might have no subject matter expert in its staff, but might provide a qualified trainer-assessor who acts as a broker between students and subject matter experts.
Subject matter experts might be from the enterprise overseeing practicum students, or act as separate third parties in an "adjunct faculty" role. They are listed in the formal paperwork, so that the RTO can show that it has adequate subject matter expertise.
It seems to work most easily for portfolio assessments
As the SNR requires the RTO to have staff for what it does, it may need to have some way of satisfactorily documenting them as a adjunct staff member.