Used to work with a guy that had had a tiny drip of HF acid on his hand.
He had a hole about 4mm diameter and about 4mm deep in his hand. It had
been like that for 20 years. It never closed up....

Odd, more likely to be phosphoric acid that had burnt the skin, HF generally
does not burn (or rather does not give a burning sensation) on contact with
skin. It is absorbed into the body, and makes for the bones, HF antidote gel
draws the HF to the surface and neutralises it. If not treated it will work
through the body, removing the calcium from your bones. If treatment is not
forthcoming, you will experience severe pain in the affected bones,
treatment at that stage is usually amputation.