If you are using the 3M butyl(s) that comes in a strip, they include the two little 3/16"x1" rubber stops that sit in each corner of the windsheild/back glass when installing. the little ruber stops simply lay in the glass channel and hold the glass up off the bottom of the channel by 3/16".

If you do use the 3M strip adhesive be sure it's for your specific installation as you have to be sure it's the correct thickness, otherwise your moulding may not rest against the glass as they should...