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. ).

Dissimilar metals are better, steel, brass, steel washers & a bit of McLube Sailkote Aerosol 300ml

A bit old, but just an add-on...

I have a quality rivnut tool set at home, but when on the road I carry M4-M8 bolts, a nut and a washer to match each, the appropriate drill bit for each and a small bag of rivnuts (yes, M4 -M8). It all fits into a zip-lock sandwich bag (doubled for strength), little weight  and has come in very useful (for myself and others) on a number of occasions.

Cheers,

Mark

Useful for the odd riv nut here & there, but the low cost of an air operated riv nut tool if doing a few is well worth the expense if you have an air compressor.

I've had one like this for years & used it a lot. https://www.ebay.com.au/itm/334555065739

This is my riv nut tool.

Good for riv nuts from M3 to M12. Cost $86 ex Ebay.

This is one of the uses I put it to.

Put riv nuts into some scrap aluminium sheet.

Glue the sheet to the panel with Sikaflex (in this case 1.5mm of fibreglass skin on the underside of the OKA sandwich panel floor).

The protruding ends of the riv nuts are recessed into blind holes.

The mounting plate (in this case for a hot water expansion tank) is bolted onto the riv nuts.

And the expansion tank is attached to the mounting plate.

Using this method, quite large or heavy parts can be attached to otherwise thin sheet without causing any high stress load points.

Cheers,

Peter