Considering the definition of the
Equal Tempered where a semitone is calculated by dividing the octave relation (2:1) on 12 semitones on a equal scale.
Therefore, a semitone, based around the 440 kHz, is calculated by:
st=440*2^(1/12)
And then, you need to solve the equation, for x:
432=440*2^(x/12)
x=-0.317666594733664
Which is the cents below the reference 440 kHz, so you should set the fine tunning to -32
