More on Favored Enemies
here. Quite a discussion on whether or not the bonuses apply if the Ranger doesn't know what he's fighting... and HOW he knows! I, myself, am firmly in the camp of "it always applies, regardless". YMMV.
No real answers on making it apply whenever the
Player wants, though. The Smite option works, but is too limited, IMO.
As I said, before, my solutions are:
1) The bonuses always apply, regardless of whether or not the Ranger knows what he's fighting.
2) Favored Enemy (X) adds Knowledge (Whatever contains X) to the Ranger's skill list (this is already determined, in 3.5e), AND the Ranger may add his or her Ranger level to any such rolls, only when trying to know things about his or her favored enemies, being treated as skilled even if unskilled. For example, FE: Undead adds Knowledge (Religion) to the Ranger's skill list, and a first level Ranger would add +1 to his Knowledge (Religion) rolls to know the DR of a Skeleton, even if he hadn't taken Knowledge (Religion), yet, but would be treated as unskilled if trying to recognize the "Holy" Symbol of the evil temple it was guarding!
Again, I don't worry about the FE Bonuses applying whenever *I* want, as I have played long enough to know that ANYTHING will show up, sooner or later. Hunters are patient...