The attributes which are ONLY specific to Allah and not used for human being , those arent allowed to use. but you can use accompanied by Abd' or 'Ubayd or Amah like Abdur Rahman, Abdul Matin. As long as i can remember there are some Attributes which are also used for human, those are allowed to use without adding abd or Ubayd. Now, is Karim also used for normal human,, i dont know. you gotta ask ulama or knowledgble brother and sister may share their knowledge about it. There was an article about it, but i cant find it now.