How exactly do I use Beat Finder?

Beat Finder does not seem to find the actual beats. I need to figure out the actual beats so that I can insert 4 more or 8 more at certain points in the tune. I thought that Beat Finder would be of help, but it is giving me pretty random information, no matter where I set its threshold. I must be doing something wrong. Is there a way to find the precise beats of a song? I am suer that it was recorded to a click track.