I understand that if the RF item is blank then there is no RF input and you can not receive over-the-air broadcasts. I thought all sets had and RF input, but maybe I am wrong. Maybe they do not ihave an RF input if they do not have an internal tuner, which would make sense. All sets do not have an internal tuner; they expect you to have cable or satellite service, and the tuning is done on those boxes! I just got a new set recently that has an RF input and an internal digital tuner and I am getting excellent high definition reception of our local channels over-the-air using an old style outside antenna:-)