Schmetz Twin Stretch Needle (4.0/75)

To create 2 parallel rows of stitching, especially as a hem for knits that duplicates the look of a cover hem machine, this is the wider one of your two choices.  
The needles have a rounded tip as in the Stretch Needles - most suitable for knit fabrics. 

Londa says:  "Be sure to stabilize with stretch interfacing on the Hem ALLOWANCE and to lower your needle tension a bit to create a non-tunneled, nice look on your knit hems.  
See my knit DVD for many hints on stitching with twin needles:  Stretching Your Knit Sewing Know-How.