I'll do my best to break down the technique slowly.
Firstly, most people think switch means you swap your legs around - don't do that, it's what beginners do but all it does is give you a massive telegraph.
When you swap your legs around all you've done is announce that you're going to throw the kick and thereby you lose the distance, at best you're only going to connect well with the end of your foot and at worse you've been knocked out.
I used to use the leg swapping technique, then I decided to start copying Kru Dam from Sitmonchai's technique, and it works infinitely better,
Kru Dam breaks it into 3 steps:
1) Drag your lead foot back a small amount, around 6 inches
2) Bring your front leg forward in front of your lead leg
3) Kick
Doing this allows you to eat up the space between you and your opponent and it allows you to chase him down without. You will find it awkward at first, and that's okay, but the speed you get with it is SO much faster than the standard method, but unlike bringing your lead leg straight up, it actually has power.