Extension pronunciation of internal and external extensions?

You should still read tuò. Yè refers to a gesture intended to converge; Abduction refers to a gesture with vertical intention. The Extension here means outward and extension. So it's better to read Tuo.

If you pronounce tà, it means rubbing, that is, covering an object engraved with words or images with a layer of paper, beating it to make it clear, and then painting it with ink to make the words and images appear.