the shin, to pierce, to touch
踦 centers on the lower leg and actions involving it: the shin, piercing or touching with the foot or leg. The meanings are loosely connected through the idea of the leg making contact.
踦 combines 足 (foot) with 奇, which likely contributes the sound. The exact historical development is uncertain.
The left side is 足 (foot/leg). Picture a shin being touched or pierced by something sharp near the foot: 踦 is the shin or the act of touching/piercing with the leg.
For キ, imagine a key touching and piercing the shin: key -> キ, and the key makes contact with the leg.