You want a low shank 1/4 inch foot for the Featherweight. I've ordered from the shop listed above before. They are quick and efficient. There is another shop that also has an ebay store. I think it's called Sew Vac USA. I've also ordered from them before and been pleased.
Congrats on the Featherweight! You'll love it! I've had mine a couple of weeks and am very pleased I bought it.