Please refer to the original equipment manufacturer's manual. The procedure will be in there.

Every manufacturer has a different detailed procedure. In general, in addition to the HART communicator, you will need a pressure source that is able to provide full range pressure and a precision test gauge that will cover roughly twice the full range. The reason for this is that gauges are most accurate in the middle of their range. The typical procedure is to zero the transmitter with no pressure, then apply full transmitter pressure as shown by the test gauge and check the transmitter reading. Adjust the transmitter reading to match the test gauge. Go back to zero and recheck that. Repeat this cycle until you no longer need to make adjustments to the transmitter. When you are done, compare the transmitter to the test gauge at 0%, 25%, 50%, 75% and 100% to check for linearity.

This article will provide an authoritative overview for calibrating HART instrumentation:

http://www.hartcomm2.org/download/calhart.pdf