Most all of the higher end machines can do a "hand" stitch. Gerry is right...it is the bobbin that you load invisible thread.
There is a quilting stitch on the D1 that you use invisible thread in either the top of bobbin...I can't remember which...which gives it a look of hand quilting. If you can't find the info in your book that came with the machine, PM me and I'll look it up. At least I THINK it's also on the D1!
The Designer does not really skip a stitch, but alternates a triple and a single stitch. What you see is the triple, the single seems to be a space, but is not.
I wondered how that would work, a machine can't really 'skip' a stitch like a human can. Thanks for the info, Martine!! Hugs, Marji