An open toe walking foot should do the smaller twin needles. Don't try a 6.0.
If you do try, make sure you are set for straight stitch, and turn on Twin needle on your machine. Twin needle usually limits the needle movement for other stitching to 4mm. This should fit very well in the openings of the foot and your sole plate. This way, if you make a mistake by not selecting straight stitch when you start, you won't accidentally hit the sole plate and break needles, or if you are using a fancy stitch, it will keep that stitch in the right limits.