Xanthum gum? Missing ingredient

I haven't made this recipe, but based on other recipes I've seen for muffins using gluten free flour + xantham gum, I'd use a scant 3/4 teaspoon. The general rule for muffins and quick breads is 1/2 tsp per cup. This recipe has about 1 1/3 cup of flour, if the conversion table I consulted is accurate.

Let us know please if you try it, and how it turns out! Thank you. ;o)