Free motion quilting is usually done by dropping the feed dogs, so the foot doesn't really matter. I have used a regular wide zigzag foot, just because it allows me to see better than a narrow foot. No foot is required to FMQ, you guide the fabric under the needle, foot only helps keep the fabric feeding without wrinkles ahead of it. You can also leave the foot off completely (make sure to drop the foot control) but must be extremely careful of fingers!