GG, I like the idea of joining the live ruffle sts to the sock as it's knit top down. It's a neat way to do it. The ruffle will be oriented in the upward direction but will bend over toward the heel.
The only way I can see to get the same orientation of the ruffle as the photo is to start at the edge of the ruffle, knit the length you want, decrease quickly over 1 or 2 rows and knit to the top. Then go back to pick up sts, say at the row after the decreases and knit down to the heel. However, I don't know if this will make an annoying ridge.