Hi. I would like to try this fondant recipe. However, the recipe calls for glycerin and I haven't been able to find it. Are there any suggestions of where I can find this? TIA

Yes. Hobby Lobby or Michael's carry the little 2 ounce bottles of Wilton glycerin. You can also get glycerin from Wal-Mart pharmacy or most any pharmacy. Just make sure that the glycerin that you buy in the pharmacy is 100% vegetable glycerin with no additives. The pharmacist can help you with that.
You can also buy it at health food stores. It's used as a natural sweetener. MFF is 'hands down' the best fondant that I've ever tried. I make several batches each week because I just don't like using anything else. Just be sure to follow the recipe exactly as it's written and strain the gelatin/syrup mixture...I strain mine through cheesecloth. If you don't strain the liquids you will end up with solids in you fondant. I ruined an entire batch doing that once. You can't strain through a mesh strainer you need to use cloth and cheesecloth works the very best.
I also use her "updated" fondant recipe.

You're welcome. Here's a couple of tips for you. SIFT all of your powdered sugar. I add an entire 2 pound bag to my mixer and pour the LUKEWARM (it shouldn't be too hot or too cold) gelatin/syrup mixture and start the mixer to knead the fondant. Once the 2 pounds is almost fully incorporated I start adding about a cup of ps at a time. I continue to add ps until I can stick my finger into the fondant and it leaves an impression of my finger BUT none of the fondant sticks to my finger. If you stick your finger in and any sticks to your finger you need to add more ps. I think a lot of times people aren't adding enough ps to begin with which causes their problems with this fondant. I use all but a cup or two of the 3 1/2 pounds of ps when I make MFF.