Contrary to its name, Goatskin isn't a goat in Kingdom Come: Deliverance 2. He's a crucial character you must locate during the "Into the Underworld" main quest in Kuttenberg. Katherine will direct you to the inn, but finding him requires some detective work. Here's a simpler method:
Goatskin hides in a barn above the Black Horse tavern. Access the barn behind the tailor's shop and climb the ladder. Remember, this is a private area, so stealth is key.
Once upstairs, drop into the courtyard, climb onto the carriage, and enter the adjacent barn through a window. Climb to the top level – Goatskin awaits. This strategy only works during the day; he changes locations at night. Saving before speaking to him is advisable, as dialogue checks determine your progress. Failing these checks could cost you 150 groschen (or a hefty 500 groschen if you fail again).
For more Kingdom Come: Deliverance 2 guides, including romance options and optimal perk selections, check out The Escapist.