This is the monogrammer, which fits onto the machine just like the automatic buttonholer, and works in a similar way.
But there is a caveat: You have to have this feed cover plate in order for it to work properly and it does NOT come with the monogrammer and they are actually hard to locate. I got this one for almost nothing in a box of Singer attachments I bought at a yard sale. One of those things I just happened to need and just happened to find!
Iron the plastic coated side onto your fabric. Even with this very delicate linen, it peels right off without damaging the fabric.
Use the letter placement guide to find the exact spot to start stitching