The enemies shouting insults at the king is spoken of as if insults were an object that the enemies throw violently at the king. (See: [[rc://en/ta/man/translate/figs-metaphor]])
Here "footsteps" represents where the king goes. Alternate translation: "they mock your anointed one wherever he goes" (See: [[rc://en/ta/man/translate/figs-metonymy]])