probably If the Sky Box is that "old" then, as satelliteman said, you will have both the main RF1 o/p, and that should be feeding the 1st TV, and RF2 can be used to feed the 2nd one (that's part of the reason it is there) - so, easy way, just run a cable from RF2 to the 2nd TV.
If, however, you have to run both TVs from the same wall outlet, then a simple passive antenna splitter would do the trick if all the cable lengths are not too great - both TVs will get the same signal, with the Sky box still being controlled directly by your original Sky remote.
Nevertheless, if you want to use the facility whereby the Sky box can be remotely controlled by a 2nd Sky remote associated with the 2nd TV, then you need one of those small distribution amps which pass the IR signal from the 2nd remote back to the Sky box via RF2 - the first amps came from Global Communications, but I think there are clones now, and you also need a "TV-link"-type IR receiver and "eye" near the second TV to pick up the signals from the 2nd remote and send them back, via the amp, to RF2.
OTOH, if your Sky box is one of the latest ones, which given its age I doubt, then those only have one RF outlet, and there is an entirely different system for adding feeds to extra TVs - can't help with those as I don't have one of those boxes, but I am sure others will be able to.
