Probably a utube on this, but drill your correct size hole, you need a nut and bolt of appropriate size/thread. Thread nut onto bolt, screw bolt into rivnut, through the thread.
Tighten nut onto top of rivnut, ie as if you were taking it off the bolt. Then hold the top of bolt in a fixed spot and try to take nut off the bolt. This squeezes the rivnut body the same as the pliers and you end up with a good job. (Takes a fair amount of pressure on the spanners with an M6 steel rivnut. ).
