I don't have much experience with stretch stitches other than the simple zigzag stitch. Since I want to finish my Renfrew top I wanted to try a few other stitches on my new sewing machine.
These are the 'advanced' stretch stitches on my machine. I don't like number 11 that much, the results with nr. 12 look better:
Number 09 is a variation on the classic zigzag, also known as tricot-stitch or multi-zigzag stitch:
Number 10 is my favorite, a combination of a straight and a zigzag stitc. Because the straight stitches there is stretch in your seam and the zigzag finishes the raw edges while sewing:
Number 12 is a sort of imitation of the overlock stitch, which is also stretchy and gives a neat edge finishing. Warning: this one uses a lot of thread!
Here is a little stretch test for comparison:
I used a 'walking foot' because I found that the knit fabric was stretched too much with the regular foot. This resulted in wavy seams, not handy on clothing. The walking foot is designed to help with the transport of multiple layers of fabrics. It does this by helping with the transport of the upper layer of the fabric, the feed dogs in it move simultaneously with the machine's feed dogs. Here is the walking foot in action.
EDIT: Added here a close up of the walking foot (yes, the white box at the back is also part of the foot):
1. The fabric is held down before the needle goes down:
2. The transport part is lifted up (and makes a step forward) when the needle is down:
Another option could be the 'tricot-foot' which I don't have (yet).
This one is made for the same purpose: even feding the faric layers, especially for thin layers and slippery fabrics. It works differently, there is a small piece of rubber (blue) under the foot that helds the fabric down when the stitch is made and releases when the transport feet move. According to some reviews on the internet it should be working just as fine for knits as the walking foot: