gosh- i've never even heard of a 'ruler foot'...using the (base) so you have a flat surface to hold your ruler on- you just use the side of your hopping foot...which is why it's important to use rulers made for this- our cutting rulers are too thin- the foot can jump up onto the ruler- the quilting rulers are 3/8" or 1/2" thick-so the foot just travels along the side of the ruler.