Yes, it is possible to reduce the generated .rpd file size. The generated .rpd file size is the same size as the flash or configuration device it is targeting. Thus the size of the .rpd file will not change even though you enable compression mode.
In order to reduce the .rpd file size, follow the steps below:
1. Open the text .map file that was generated when you generate a .pof file.
2. Refer to the end address in the text .map file. The data byte starting after the end address is not the configuration data therefore can be discarded.
3. You can use any binary editor freeware to view and edit the .rpd file.
4. Go to the end address location and remove the data bytes starting after the end address.
5. Save the modified .rpd file.