Gently clean the area where the scuff is located. Use a slightly damp cloth to clean off the area, or use a leather furniture cleaner according to the package directions.
Warm up the area where the scuff is located with a hair dryer if your couch is made from aniline leather. Use a soft cloth to buff the area and see if the scuff comes out. If it does not polish out on its own, you have to treat the scuff like you would a scratch.
Apply some leather conditioner to the scuff and buff the area with a soft cloth to try and clean the scuff without having to apply a leather repair product.
Use the scouring cloth or sandpaper included in your leather repair kit to slightly rough up the area where the scuff is present. If you don't have a complete leather repair kit, use the finest grit sandpaper you can find and lightly buff the scuff.
Use the leather repair product from the repair kit as directed. Be sure to use any pretreatments that are included with the kit if it comes with more components than just the sandpaper and leather repair solution.