How to sew a knit fabric with a straight stitch machine?
Yes, you can sew knit fabrics with straight stitch. Notice t-shirts, they are made of knit jersey. When you sew woven fabric on the bias, that creates stretch on an otherwise non stretchy material. Here are tips, when I get somewhere with a better signal, I will upload pics to demonstrate.


You want to be sure to use a ball point needle for knit fabric.
Where you sew, will have less stretch the shorter the stitch-see pics not stretched and stretched.






Fray. The part that worries people about sewing knit fabric without a zig zag or overlock, is that it may fray. A few options - French seam, double stitch, use fray check 
If you’re concerned about jamming your machine, do not pull the fabric or it will become wavy. You can use stabilizer to strengthen the seam.


Hope this helps. Here’s a pic of a jersey knit skit I made as well. 

It’s an elastic waist and the ruffle at the bottom is woven eyelet fringe.
It’s great.
Good luck!