Honorbuddy Calculations on xp/hr

[chemical]

my question is on how HB is calculating my experience per hour. reason i ask is at the moment I'm boosting a couple of toons and currently around level 74. Hb says I'm getting around 485k/hr. though i'm really getting around 2x that or close to it 850k/hr?

Does it not pick up "Recruit a friend" bonus points? does it read my exp that the wow screen post what I'm getting a kill? just wondering that's all