Sorry, can't help with FREQOUT but if I'm not mistaken the 12F615 has a PWM module, I'd suggest you use that.
Create a lookup table for a sine function containing say 20 entries. Cycle thru it at 1ms per step and you have your 50Hz output.

But then generating a 50Hz sinewave may be a job for some analog circuitry instead of a PIC.

/Henrik.