A recording and mastering engineer associated with King Studios Cincinnati, OH and often appears on releases associated with the 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.