I don't know the word presser foot should be used; it is a seam guide. My one viking has one that screws into it but you can also buy one that is a magnet that you place on your machine bed. It holds very strong. Most Joann's, Fabric Hut, and even Walmarts have them; they are around $5. It was a must when I was teaching my sister to sew and couldn't produce a straight seam.