Potassium Iodide or KI contains roughly 76.4% Iodine. SSKI is Saturated Solution of Potassium Iodide. The magnets
will affect the Iodine in your SSKI .
As to the strength of the magnets. I have experimented
with magnets that pick up 30 lbs to over 175 lbs and the weaker magnets seem to have just as good an effect.
So if you have magnets that tend to pinch your fingers as you apply them to your bottle of SSKI you should be fine.