You can only rep around 5 people in 24hours it seems.
Withing this limit you can rep a single member once and then you have to give out x amount of rep before you can rep them again.
The rep id is the same as the permalink id for the members post.
Each time you get your rep clicked you get 25 credits.
If the member who clicked it had rep points of 5 or over then you get a
which is a +1 rep.
If the member has 4 or less rep points then you get a
which is +0 rep.
eg: I have 32 rep comments, but of which only 20 people had rep points of 5+
Rep break down(correct me if I am wrong) :
0-10 points -> $nick is on a distinguished road. (rep power 1)
11-20 points -> $nick will become famous soon enough. (rep power 2)
21-25 points -> $nick has a spectacular aura about. (rep power 3)
26-30 points -> $nick is a jewel in the rough. (rep power 4)
31-35 points -> $nick is just really nice. (rep power 5)
36-40 points -> $nick is a glorious beacon of light. (rep power 6)
41-45 points -> $nick (rep power 7)
46-50 points -> $nick (rep power 8)
51-55 points -> $nick (rep power 9)
56-60 points -> $nick (rep power 10)
61-65 points -> $nick (rep power 11)
66-70 points -> $nick (rep power 12)
71-75 points -> $nick (rep power 13)
76-80 points -> $nick (rep power 14)
81-85 points -> $nick (rep power 15)
86-90 points -> $nick (rep power 16)
91-95 points -> $nick (rep power 17)
96-100 points -> $nick (rep power 18)