This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 齽 is uncertain. It combines 齒 (teeth) with 禁, but the original semantic or phonetic role of 禁 in this character is unclear.
Since the meaning is unclear, focus on the shape: a complex character with 齒 on the left and 禁 on the right. Imagine a forbidden (禁) tooth (齒) that is mysterious and undefined.
For キン, imagine a king (キン) inspecting a strange, forbidden tooth: the king's presence helps you recall the reading キン.