I always wanted to say that. :^ ) Yes, you put the cement on both sides. The trick is making sure everything is measured and cut to length before you apply the cement. You should even draw a line on the side-bar where the rail-rug is going to go. Also remember not to stretch the rug when applyiing. Apply cement to both surfaces, wait the recommended length of time then apply the rug. Start from one end applying the rug (remembering to stay on the line) and work your way to the other. After the line side is tacked down, roll the rug down across the rest of the side-bar, starting from the center and working your way to the ends, one side at a time. Loose cement removes from the rail without a problem (using a razor blade) so it's O.K. to go a little over the line when applying it to the rail. I think they recommend that the application of the rug should begin 1/4 inch (or something like that) from the inside of the rail. I hope this all makes sense.
Anyway, mine turned out great. Hope yours does too.