Played with the pattern, CO 66 sts (6 cables of 11 stitches) to avoid the ribs on the back of the leg. Lengthened each cable by 4 rows and offset every other cable by 16 rows.

Prethought heel over 32 sts.

Foot: Instep in pattern over 34 sts, sole 32 sts.
Worked every 4th round (i.e. the second round of mint colour) of the sole stitches as a “k1 slip 1” so that the sole spreads only as far as the instep.

Thanks a lot to Sari Suvanto for this beautiful pattern. The translation of the chart by lorraine3289 is very helpful.