I discovered this only today. I set up a 'old' machine near my kitchen this afternoon instead of sewing upstairs where I usually sew. The floor is wood and this old foot feed is metal and I was afraid it would scar the floor.
Looking around my kitchen for something to place under it I spotted a silicone potholder/trivit I had purchased at Bed/Bath and Beyond with a coupon. It was perfect.....no skid........perfect size. Hope this helps.