All the the kit I have bought in the last few years has had RF-IN and RF-OUT, presumably so that the same aerial feed can be used for both the new box, and whatever used the feed before, without having to introduce RF splitters and adapters.
In fact my weird Sony Freeview-PVR, has "Digital RF-In", "Digital RF-Out", "Analogue RF-In" and "Analogue RF-Out", so my aerial feed goes...
From aerial -> Sony Digital RF-In
Sony Digital RF-Out -> Sony Analogue RF-In
Sony Analogue RF-Out -> TV Aerial socket