As the others have said, just push it as far up as it'll go and leave it there.
I find it makes me really wired and hyper so I use it in the mornings or I'll stay awake half the night.
I was using it this way already while asking for permission, which I eventually got to continue so long as the dose is the same 200mg as prescribed for taking orally.
I still get some heartburn and reflux taking it vaginally, but not nearly as much as orally, I was close to taking myself to A&E with that pain.