No. I haven't, but that does not mean it will not work for you.
Depending on what type of fibroids you have, supplementing a few (3 or 4 or 5) drops via tampon may help.
You also may want to read Brownstein's book on Iodine, why you need it, with general information on the subject of iodine.
I wrote a book on my experiences with treating fibroids alternatively. "The Fibroid Challenge", and include detailed information on how the Iodine supplementation worked/worked out for me if you are interested in details, but, unfortunately, no, they did not shrink, which was my goal also. I aborted one, and that is why I suggest it depends on the type of fibroid you have. The ones in my uterine wall remained unaffected; that is at least what the ultrasound pictures said ;-)
The book is on currently on sale!