I looked at the floor plan of a 2007 3075RLF that is for sale at Wana RV in Shipshewana, IN. I could see no difference in what they showed and what I have in a 2008 3075RL. Perhaps Keystone Customer Service could shed some light.
When I bought my 3075 from Tiara RV, there was no listing for a 3075RLF on the Keystone website. Your guess is as good as mine...front?, final?, fixed?, etc???
Several different websites across the country list a 3075RLF for sale. If you do find out what the "F" means post it for us. Good luck.