You cannot enter REM/Real Ear Measurement.
Professionally fit hearing aids use your paper audiogram (or a digital version) to enter your hearing loss into the fitting software, and then use an additional measuring system to achieve REM/Real Ear Measurement. These settings are stored in the hearing aids.
If your hearing aids have already been professionally programmed using REM then you will want to save the important original professional settings to the database before you make any changes to your hearing aid settings.
Source: DIY School PDF file (02 How to Program Your Hearing Aids)