There are two types of points. The first is scoring point, as described in the help section of the HTC home page (look on the home page under help/scoring).
The perk point scoring is done based on a set value for both your plane, and the enemy plane. Lesser planes tend to have higher perk ratings, more capable planes have lower values (though this may appear backwards, it all works out properly in the end). Killing a more capable plane in a lesser one yields more perk points (and vice versa). Again, the landing vs non-landed kill forumlas seem to apply. I seem to remember it is your perk value over the enemy plane perk value. eg. If you were flying a 30 value plane, and the enemy was in a 15, then 30/15 = 2 perk points. Or something like that. Reversed, the other plane would only get 0.5 perk points for shooting you down. This is the base value and is only accurate if you successfully land you kill. The non-landed modifiers (bailed/ditched/etc) are applied if you don't land.
It's hard to say exactly what your perk points will be, it depends on the exact matchup of planes. I know I got 10 perk points for killing a 109 in a C47 once though
At least that's my understanding of the whole thing though I don't often worry about perk points.
-Soda
