Fitting trim at base of windows

[P1800Ray]

I need to fit a couple of chrome strips that push into the panels at the base of the windows (top of doors not mid way on the panels). Do they just push in place or is it best to put a sealant around the holes to stop water seeping through? If so, what sealant is best?
Thanks

[P1800Ray]

Having spoken to Simon at Brookhouse, apparently car body caulking is used, which he's sending me.