Start with the gentlest method that works and stop as soon as the rust is gone. Oil the spot, leave it a few minutes, then rub with a cork, a wine cork end, or a folded piece of denim. If that fails, step up to 0000 steel wool or a fine abrasive eraser, always working along the blade rather than across it.
Surface rust sits on top of the steel and lifts with very little abrasion. Put a drop of light oil on it, let it soak, then rub with something softer than the steel: a cork, denim, or a folded paper towel with a little bicarbonate paste.
Rushing to sandpaper is how people turn a small orange spot into a permanent bright patch that never matches the rest of the finish.
If gentle rubbing fails, 0000 steel wool with oil is the next rung, then a fine rubber abrasive block. Work along the length of the blade in the direction of the existing finish, not across it, so any marks you leave blend in.
Stay off the edge bevel with abrasives. Anything that touches the apex changes your edge geometry.
Once rust has eaten a pit, the steel is gone and no amount of polishing brings it back. You can clean the pit out so it stops spreading, but the dimple stays. That is why catching rust early matters.
Afterwards, dry the blade and oil it. See does stainless steel ever rust for why it happened.