You are doing it right. Holes in the template with nails pushed in. One thing that might make the hot wiring go a tad bit smoother is to put parifin wax on the bottom edge of the masonite template. That way the wire will run smooth and not burn in the little groves.....I hate the little groves....you know what I'm talking about.
No need to use tape or glue or anything other than nails or screws.
I also like to hold the hotwire tool with my hand the other way, that way you can apply more presure on the palm of your hand and cause less fatigue....and get a better wire cut.
This is me in the picture, and I use 8-penny nails about every 18 to 24 inches apart. I hold the hot wire in this manner to cut the bottom rocker, which allows me to apply upward pressure on the wire. Resinhead is correct with the use of parifan wax to help make the wire slide easier. Cutting the upper rocker is easiest, just keep a low angle on the hotwire frame, and push evenly and slowly...
mmmm putting the template on top. That is a good tip. I used tape both on the deck and on the rails as a guideline but using the template is a much better option. I prefer hotwiring the rails as well cause it gives me a lot less dust flying around (actually my wife prefers it, and since her mood improves when I produce less dust, i guess I prefer it as well. Though shaping rails with a planer is more fun)
I'm going to cut my blank out of a EPS block that is 1200mm x 2400mm so that is going to be a lot of work with the planer if I should shape it from there.. so no, i'm going to rughly cut the rails, and THEN use the planer..
But will have to try both solutions (tape and nails) to find out which one is the best.