When trying to size the sock to fit my feet, the big thing to worry about is the size of the toe. For the February sock pattern, the toe is created by casting on stitches and then using the wrap and turn technique to create the toe. It's not a true "toe-up" pattern - it's more like a "toe around" pattern.
Measuring to confirm the size of the toe starts by figuring out how wide the toe box should be. That's accomplished by measuring across the base of the toe, as shown in this picture:
From the picture, you can see that the correct width is 4". Double that to 8" and that's the "circumference" of the toe box. Here's a picture of the finished toe (and the start of the foot):
Changing the sizing for the foot itself is a little more difficult as it requires understanding the pattern repeat. The instep is a 2 x 1 (3 stitch) repeat and the sole is a 2 x x (4 stitch) repeat. I'll talk about that when I have time later tonight.