Identify what your recipe needs butter extract for: aroma only (finish), or flavor structure (cookies/cakes).
Pick the closest substitute from the ranked list, then use the ratio as a starting dose (extracts are easiest to match 1:1).
If your substitute is liquid fat (ghee/browned butter/melted butter), reduce any extra added liquid by a small amount to keep batter consistent.
Mix the substitute in with the wet ingredients (or blend crumbs into dry) and bake as written.
Taste after baking and adjust next time: add a small extra amount if flavor feels flat, or add salt if it lacks “buttery richness.”