if you meant to ask:
How can I use radio to determine if line-of-sight exists at a distance beyond what the naked eye can see?
then I would say:
Using a frequency of something with sufficiently narrow beam-width, yes, you can determine if pracical line-of-sight exists between two points.
A laser may be sufficiently narrow... but it may also be too narrow in that the aiming precision required may give the impression that you don't have line of sight when, in fact, you just aren't able to suitably control targeting of the transmitter and receiver.
Microwave dishes, UHF yagi arrays, or even just a single UHF yagi may be 1) of sufficient beam-width to make aiming feasible and 2) of sufficient narrowness for the purpose.
Given modern ability to measure precise location with GPS and calculate relevant antenna bearings, you might even look into using computer calibrated and controlled antennas to accomplish this.
The actual distance between your 2 points will matter, as will atmospherics (temperature, humidity, precipitation, etc) and other environmental factors.