to select, to pick out from, to discard, to expose, to reveal
擿 centers on the act of singling something out with the hand: selecting, picking out, or discarding. The meanings of exposing and revealing extend from the idea of bringing something hidden to light by picking it out.
擿 combines 扌 (hand) with 適, which likely contributes the sound and may relate to the idea of going directly to something. The exact historical development is uncertain.
The hand radical 扌 beside 適 suggests a hand reaching directly to pick something out. Imagine a hand selecting one specific item from a pile and discarding the rest.
For テキ, imagine a hand picking out a tech gadget from a box: tech -> テキ, and the hand selects the right one.