As an alternative to Google Maps, RSForm!Pro now offers the possibility to use the OpenStreetMap plugin which once installed and configured, you can add a new field in your form, more precisely, the OpenStreetMap field. You can refer at this plugin's Guide for more information on how to install, configure and use the new field.
You can choose from OpenStreet, Mapbox, Thunderforest, Stamen or use your custom tyles: