KI is potassium iodide. It's easiest to use in the form of SSKI which is a saturated solution of KI. You can find out more on the Iodine forum, there's lots of info there.
What gave me the idea to use it was partly it's use for ulcerative skin diseases which are often caused by UC.
I figured if it works for them then why not UC itself.
I posted a link to the dermnet site on the UC forum before but here it is again
Depends on where you are how you get it. I bought pharma grade crystals from a chemical supplier in the UK. Trapper sells SSKI on the Iodine forum but only in the US.