RG (10)

A recording and mastering engineer associated with King Records (3).

They can be identified by "RG" etched in the runout grooves of vinyl format releases.
Please note that Rob Grenell also can be identified by a 'RG' etching. However, unlike Grenell's etching, this engineer hand-etched the "G" in cursive.

Possibly this is the Bob Green listed as Mastering Engineer at Starday-King Recording Studios in BB 1971-09-18, see link.