I've already answered this question on your other post. (Thanks for the reply, by the way).
However, I'd like to urge caution when reading CF's reply. As I explained on my other post, a few Freeview boxes have built-in modulators. The 'RF out' on these boxes can be fed to a TV's aerial socket, so that you can view digital TV. (Exactly as CF says).
However, many 'ordinary' Freeview boxes also have a socket labelled 'RF out'. This socket only provides 'RF loopthrough', i.e. what comes out of that socket is exactly the same as the what comes down your aerial. (If you connect it to your TV's aerial socket you'll be able to get analogue reception, but not digital).
My point is that, just because a Freeview box has a socket labelled 'RF out', it doesn't mean that it's got that all-important modulator inside it. Look for the word 'modulator' on the box (or in the description on a website). Don't assume that 'RF out' is a sufficient description.
Chris