Nutsert tool

[COFFMAN]

One of my favourite tool great for adding or securing excising bit a pieces in the engine bay, neat and tidy. Have the pop rivet type ones. Came with about 4 or 5 different type inserts. You can buy inserts from any good nut and bolt shop, the flush fitting type wouldn't be as secure as the raised ones....

[Richard buttocks]

You can use a bolt and nut to squash the nutsert
works fine and you probably already have 2 spanners....

[LeighP]

I used to use the two spanners/bolt-mandrel procedure to hand fit rivnuts...worked OK probably 90% of the time, but its painfully slow.
A while back, I picked up a hand setting rivnut tool off Ebay from a guy in the Newcastle NSW area....he put together a tool and kit with a stack of inserts and different sized mandrels - a much better way to do it, if you're just doing the occasional rivnut jobs - was good value for money.
That Dafra tool in the video is one of the best I've ever seen......if the price was reasonable, I'd buy that one.

As to your question, the hole should be a tight fit for the rivnut insert, do not lube the rivnut with anything....you want it to grip firmly.