It's better to use 3 point Cap for now ...
4 dots cap is for compatibilty only (for old freetrack users ...) - You can use it if you want .... But it's better with 3 dots cap ...
Use freetrack software dimension for build your 3 dots cap ! (in freetrack 2.1 there is sometime a small bug : NAN error ....
It can be solved by changing your front top LED dimension ...
Don't forget to select correct tracking model in "model" tab .... if not, freetrack head preview will be crazy ...
Don't forget to have good FPS (like your real FPS webcam in "cam" tab) values in "interpolation" in global tab ... (it's important for good tracking speed result ...)
Read Handbook for more explain !