Yeah just like a rivet. It needs setting in place before you attach something to it as it takes quite a lot of force to crush it. A lot of the tools look like rivet guns but they have an male thread on to which the rivnut is screwed. Put it in the hole then operating the tool pulls the thread back out (like the pin of a rivet) and crushes the fitting in place.
I just use a home-made setup a bit like this:
Tightening the nut while holding the bolt still effectively crushes the rivnut as it pulls the bolt thread through it.