I haven't ever used this yarn, nor knit this pattern, but there're things wrong all over the place. First, it tells you in the yarn that you may need to go to a larger sized needle because of the elasticity. Which makes it sound as if it's likely to shrink up. But I would have thought that with a very elastic yarn that you would have to do DOWN a needle size, that it would likely knit too big otherwise. Then, in the directions, it says that you should let your swatch rest overnight in order to determine the real gauge. So what does that mean in terms of the finished sock? That every time you wear it, you can have it on for 1 hour and then take it off and let it rest overnight so that it will go back to its proper dimension???
Are we baking bread or knitting socks??? Also, the yarn says it should be 4 -5 sts per inch, but the pattern wants 7 sts per inch. Even with the 7 sts, 64 is gigantic. The basic sock pattern I use most has 50 sts cast on with 7 sts per inch. So 48 makes more sense, but no matter what, I would be very suspicious of using this pattern for this yarn, and if I did use the pattern, I'd be working with a 9 sts per inch yarn, and one where there were no "let it rest overnight" directions.