Reverse F has other indicators to mark it also....
Interestingly enough, when you see a reverse F, you will know it for certain as it is so distinct. .
Not home now so I can't post any for you to see...
Hi Jim picture below of a 5-f . Note the main on the helmet is broader , and the prominent rock where on the D type coin the signature would be. On this well worn coin it is quite distinct . If the rare type indicators are not there , I can't see it being of any worth , Terry