200km, or the range limit of its propellant, or line of sight where it is used
The range for operator guided missiles and drones is equal to the range of the comms device used. However, the actual limit per the rules is that the gunner cannot guide the missile, regardless of the comms used, to a target he cannot see. So therefor the actual range of the missile is whatever the line of sight is to the target, as long as that range does not exceed the range of the comms device.
So:
a 200km radio guidance package means the missile, if it can even fly 200km, has a theoretical range of 200km. The line of sight may only be 30km so that will be its actual range limit.
There is a sidebar to this, though. Like all comms in Striker there are jammers for radio-guided tac missiles. So while having a 200-power radio for a missile that may only have an operational range limited by line of sight and it's propellant's capability may seem extreme it would mean that jammers of a lesser power would have less chance of jamming the missile. The jamming rules indicate that range to the target relative to the jammer and gunner are considered, but the rough rule of thumb that so long as the radio is stronger than the jammer you have a good chance of getting the missile to its target.