Sand down the SEM problem plastic repair adhesive each time you add a coat.
Add enough coats to fill in the gap completly smooth. If you have a small divet it is ok but should look like this before moving on to the next step..
Once you have achieved the look as above it is now time to spread on the SEM no swell glaze. Remember not to use bondo, this product is designed to move and flex so that your bumper inserts that have been filled will not crack.
Use the no swell and spread it with a bondo spreader apply even coats, sand inbetween coats. Should take about two or three coats. Sand this with 80 grit and a DA.
Now sand out out scratches with 320 or higher. I recommend using 600 wet sand paper.