Auto-spacing

Space n and o (and H and O for capitals) by hand first. Auto-space then measures the white each letter already has on its sides (an o curves away, an n stem doesn't) and proposes side bearings that give every letter the same amount of space. The method follows the area method behind HT Letterspacer.

You see the proposal in sample text before applying it. Revert auto-spacing puts the old values back.