The plastic sill cover (kick plate) is held on by a push-in black clip at the top (visible), one clip at the inside rear and about 6 along the inside bottom. The door rubber sits on the top of the vertical inner part of the sill cover.

When refitting the sill cover, I found that by first inserting the sill cover under the door rubber and then trying to locate the bottom plastic clips in the holes in the sill was very difficult. This is because you have to push the horizontal part of the sill cover towards the inside of the car with force along its entire length to align the clips with the holes in the sill. This resulted in the first clip located in the hole breaking, due to lateral pressure as the sill cover was under pressure to align itself back towards the outside of the car. I was also worried about breaking the sill cover due to too much force needed to align the clips in the holes.

What worked for me was to align the rear clip in the hole and then align all the bottom clips just partly in their holes with the sill cover just resting against the door rubber. Push down on the clips to install the sill cover. Then using a straight plastic trim tool and some silicon spray (to avoid the trim tool tearing the rubber seal), lever the rubber door seal up and the sill cover down working from the rear to the front. This took a while and you have to keep levering and pulling the door seal rubber upwards along the entire length several times. The front part of the sill rubber was quite hard to get in position. The front clips on mine didn't properly hold themselves in until the door seal rubber was fully in position above the sill cover along the entire length. Finally push all clips home, insert the push-in black top clip and ensure the sill cover is pushed back as far as possible. Picture shows sill cover partially installed.