In a linear oscillator the frequency is mapped linearly from 0 (with dial set to 0) to freq(64) (with dial set to 64)
now, i don't remember which frequency the osc goes up to, if i remember correctly it's 20 kHz, but if you want to be sure read that number on the object (setting the dial to 64.
Say you want a 432 Hz sinewave (and freq(64) is actually 20khz)
x=(64*freq you want)/freq(64)
x=(64*432)/20000 = 1.3824
Click on the dial and type 1.382
You won't have exactly 432 Hz, but that's the closest you can get