I use it all the time....just brush it in as it's self leveling acrylic!
I use it for clear coat as well as tinting windshields.
To tint the windshield, first dip the windshield in Future and let it drain off, blott the thin edges with a paper towel to avoid pooling. Let it dry for a few hours. Then add food dye to some Future and repeat the first part. Let Dry. Repeat if needed. If you mess it up, just take a cotton swab and wipe it off with clear future and re apply!