Display RPMs clearly on envelope & make it easy to access beam widths @ RPMs.
Should be able to mouse near an RPM & have the curser 'snap' to the RPM, and give both the X and Y rms beam size for easy comparison to RPMs measuring the actual beam profile.
Alternatively (or additionally), have a field where you can select (drop down list) or enter an RPM name, and have it read out the RMS beam sizes at that point.