The Dept of Labor, which oversees retirement plans, publishes a brochure entitled Meeting Your Fiduciary Responsibilities, i.e. those that come along with oversight of a retirement plan. While the DOL has published a lot and there is a lot to keep up with, this is a pretty simple and straightforward introductory brochure that I highly recommend as a starter.
Pay particular attention to:
pg. 3 – Limiting Liability
pg. 5 – Hiring a Service Provider
pg. 6 – Monitoring a Service Provider
You’ll notice that the DOL, like all government agencies and auditors is big on documentation. In the DOL’s case, special emphasis is put on the oversight process and reasonable fees.