I just finished a pair of felted socks for my son's girlfriend. This is the fourth pair of felted socks I've made and I still have trouble with the kitchner stitch, which thankfully is not obvious after felting. I use Lopi light yarn and #10 needles. The heathered lopi yarns felt up very fuzzy, which I like. Here's a picture of the socks before felting:
After two hot-cold cycles in the washing machine, they look like this. See how fuzzy they get? The white cuffs don't get as fuzzy because the white is not heathered and has a carry-along yarn that I added every third row.
I decided I wanted them just a wee bit smaller, so I ran them through a third time.
Next knitting project is a beret--not felted.