What should I do if I consider that site rules are being violated in a forum?

In this case you should refer the issue to the forum moderator or a member of site staff. At the bottom of each forum thread page you will see a little box with the name of the corresponding moderator(s) and a "Call to this topic" link:

When you click on this link, a small box will open to let you describe the rule(s) violation you perceived in the thread. This is a mandatory field. When you submit this information it will be included in a profile email to be submitted to the moderator. 

You may contact site staff on the issue via support request, in the case of a forum which has no assigned moderator.