First off, the directions aren't worth the paper they drew the pictures on. It's quite easy after you screw up the first time.....
There are two bars, one for the back and one for the front. They are different sizes as the back of the WK2 is not as wide as the middle section where the front cross bar goes.
Each bar is labeled with a forward arrow, the arrow goes towards the front of course.
The crossbar has two screws on each end, only loosen the outside screw on each side of the bar, not all the way however enough to loosen the clamp guides so they can slide underneath the existing rails. You may need to do this a few times to get them loose enough to install. I have no idea what the inside screws are for. I loosen them on the back bar before I knew what I was doing and now I can't tighten them back up. The crossbars are very secure so I'm not too worried about it.
When you have the outside screw loose enough to slide under the existing rails, tighten the outside screw securely and the cross bars will be properly secured to the rails.
Rubber stripping, they are two different sizes, on for the back which is shorter and one for the front which is longer. I made the mistake of putting the long strip on the back, it stuck out an inch so I cut it off with a knife, when I put on the front strip, it was an inch too short. Fortunately I had saved the one inch cut piece and was able to use it on the front bar.
I took the lock (key provided) of each side of the crossbars and pushed the rubber stripping through the grooves. Once you reach a certain point you will need a pair of pliers to grab the other end and pull the rubber strip flush with the end of the crossbars.
The two main things to remember are the crossbars and rubber stripping are different sizes, front and back and only loosen the outside screw when trying to attach the crossbars to the rails.
It will all make sense with the parts in hand.......wjs81866
feel free to add anything as you had a few issues as well.
Personally, I think the crossbars add a little height to the back of the WK2, making it a little more rugged in appearance.