This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
揓 combines 扌 (hand) with 施, which likely contributes the sound. The exact historical development is uncertain.
The hand radical 扌 beside 施 suggests an action, but the specific meaning is unclear. Imagine a hand performing an unknown gesture.
For シ, picture a hand (扌) making a shushing gesture: shh -> シ, as if the kanji's meaning is a secret.