You have somehow misunderstood what the activity feed does. If you e.g. set the domain name to "https://www.kentico.com/" you will see what other people likes, recommends or shares on the kentico.com site. It does not (and cant) show recent activities (timeline) of any user. It would be a huge security issue if it would be that easy to show anyone's private profile activities.
So what you probably want to do is not possible. You may find better and more precise information and overview of available plugins at http://developers.facebook.com/docs/plugins/