If the rinex files are the result of field work, you should look at the notes from the person collecting the data and read what they measured for the antenna heights.
If they did not make the measurements and do not have a fixed height pole or tri-pod, you are pretty much out of luck calculating the actual elevation of your point.
Your boss mentioned 2 meters, which may suggest a fixed height pole, but I have not seen many of those that actually stay exactly 2 meters in height after a few months in the field.
