I've turned on the forum's Reputation System, as I think it may be necessary. You can make use of it by clicking the icon at the top of each post that looks like a set of scales:
When you click on this you'll get a pop up window saying
What do you think of person's
post? with the options of I Approve and I Disapprove, and a comments box. People can see, privately, the comments they received for their posts.