That's not a trivial problem.
The question is how to best modulate the RF with the analog info.
A microprocessor with a built-in RF transceiver would seem to be the best way to do that, but that's not particularly simple.
A reasonably simple and moderately accurate analog way, would be to convert the signal to a variable low frequency, such as with the LMx31 IC voltage-to frequency / frequency-to voltage converter, and use that to FM modulate and demodulate the carrier.
With a two point calibration, you should be able to obtain 1% accuracy with such an approach.
What accuracy do you need, and how far do you need to transmit the signal?