You put the report button where the "reply" button goes.

I hit report by accident about 12 times a day here because where most forums have "Reply | Quote", you have "Report | Quote".

Take a look at this mainstream forum software:
http://forums.invisionpower.com/topic/2 … h-mirrors/

Or this one:
http://sourceforge.net/dbimage.php?id=190314

It's the same on vBulletin, and all the others that I can think of.

Their Reply button is right where your Report button is.  Funny right?

Typically reply buttons go the bottom right of a post in a forum because that's where the eye naturally ends up after reading a post. (at least for we westerners)

Report should perhaps be top-right, out of the typical left to right, top to bottom flow since it's not a typical feature used when performing typical activities on a forum.