Hey GeekVishal, as far as I remember, u had a sansui furrato tv. If u still use it and have component provision in it, I strongly recommend u to upgrade ur stb.
P.S. The RF cable is used for those TVs which neither have component, nor the composite A/V ports (As Kumarbhai has shown). Such old TV's require traditional tuning mechanisms (Autotune / Manual Tune) via analog cable. Once the output of the STB is seen after proper tuning, it is stored as a channel on your tv.
The analog cable is connected to the RF out, and goes into the RF In of ur TV, where u once had ur cable wallah's connection as input.
I'm using the same setup for my grandparents' tv, and it works like a charm.