A friend of mine has been told to be non weight bearing after her ankle fracture but she has been bearing weight excessively. will her orthopedician know that she has been bearing weight by looking at her x-ray etc. ?

Likely: If she has been weight bearing we know by looking at cast and x-ray if displaced. She may have caused herself a lot of problems.

Possibly: If this was a stable fracture from the onset, then the xray signs on weight bearing will be minimal. If the fracture was borderline stable or unstable, then walking on it could displace the fracture and increase the likelihood that she would need surgery. This would be apparent on an x-ray.

Yes: She's probably in a cast or a splint. The splint/cast will probably be dirty on the bottom. It is the easiest way to tell if someone has been walking by checking the bottom of the cast or condition of the splint.