Future is, indeed, sometimes best applied with a brush. Alotta people dip their canopies in the stuff; I prefer to brush it on. It's self-leveling and brush marks will go away after awhile, unless you work it too long as DJ said. If you do get marks of some sort, you can sand them out. Future sands very well, but be careful not to go down to the paint.
I call it miracle-juice 'cuz it's VERY flexible and forgiving.
Fade to Black...