there are a few ways to identify...u need to keep an eye on her body language. below are the more general ones
1) body shake uncontrollably
2) she squirts out a clear liquid from her urethra, very much like water...dun be mistaken though, it is NOT pee.
3) if u r fingering/banging her, u might feel that suddenly her pubic muscles tighten & loosen in a rhytmic manner, this is also a sign that she is experiencing orgasm
hope this helps...
