You can also try getting Mortons un-iodized salt. We were able to find some in the supermarket.
Kosher salt should be iodine-free.
Everything I've read said kosher salt is fine on the LID. You have to avoid sea salt, though.
The thyca website that mw1943 gave you above is really wonderful. It even has an LID cookbook with tons of recipes and suggestions.
Good luck to you!
OH I feel for you..I did the LID last year for three weeks. And I used a small amout of Kosher salt. I found this site about RAI and LID. Good luck and hang in there.
Margie
http://www.thyca.org/rai.htm