[support] How to display the users real name as author?

Hi, The users of my website haves a numerical code that I want to use as login. I would like to have the users real name displayed as "posted by" on the articles (and not "posted by 65432100178"). I use the contact_realname module to define a profile_name field, but don't find how to display the users name as posted by. Can anybody help me? Thanks! Luc