Where do you put the tape for measuring RPM on a standard drilled ball?

[Hendu71]

I understand it's supposed to be tied the PAP, but I don't know where that is. Nobody watched my throw before the ball was drilled, they just did it off finger measurements.

[bowl1820]

How to find a bowler's PAP, ball speed, rev rate, axis rotation and axis tilt from Powerhouse

http://youtu.be/aicFPNb0YHw