802.01 Teeing Off
A. ... When the disc is released, ... all supporting points must be in contact only with the surface of the teeing area. Supporting point contact outside the teeing area is allowed if it comes before or after, and not at, the moment the disc is released.
If you are teeing off from a raised tee box, and your foot extends off the front edge of the tee box, is that considered a stance violation? Based on the rules, there is no supporting point in contact outside the tee box, so I would say it is not a violation.
However, if the tee box is flush with the ground, then your foot would touch the ground outside of the tee box, and that would be a stance violation.