Potassium from your diet should do. Eat lots of fruits especially yellow ones like bananas, mangoes..etc. Potassium can be found from different sources and it's rare to have hyperkalemia through diet anyway, so I think it's good.
You can eat a selection of food daily to help you get the potassium you need.
sweaty palms and feet can actually be cured naturally without using iontphoresis because it's only a temporary relief anyway. You can manage sweaty palms and feet through washing your hands after 15 minutes of typing, writing..etc. Refrain from ironing clothes when your hands are tired or when your whole body is tired. If you just finished exercising, do not immediately hit the showers, rest until your body cools down and them take a bath.
You can also boil an herbal medicine called vitex negundo orthe five leaved chaste tree. it's an herb that's really good for the skin especially for excessive sweating. Boil this and let it cool down then use it to wash your entire body without soap before you go to bed.
i hope this helps