Close analysis of the sole shot of the crocs suggests that the size is mens 9 womens 11. This ones in this pic, and this is not a criticism just an observation, are a bit worn, but it looks like that is what it says, especially compared to a new set.
There is an episode where she does take off her shoes and put her bare feet up on the desk. it is one of the later episodes. i son't recall the name, but it involved Her and louis feeling put upon for all the hard they put in.