Use very lightweight stretch fabrics;
opaque pantyhose/tights are a good fabric source. These fabrics will allow you to put the dolls shoes on!
The fit will depend on the stretch and recovery of your fabric; do a test sock to see if you need to cut larger or smaller.
The length of the sock can be adjusted from the top edge.

Sew with a narrow zigzag stitch.
Use a tear-away stabilizer under the fabric, and a clear wash-out stabilizer over the fabric, for sewing. See the Primer for Sewing with Knits file  for more information about using stabilizers and turning the socks.

1. Cut right at the pattern cutting line!
2. Fold in and sew the hem with a medium width and length zigzag stitch to retain stretch.
3. Fold sock right sides together, matching top and cut edges carefully; sew side edges with a narrow, short zigzag stitch.
4. Turn right side out and try on doll.