http://www.netknots.com/html/dropper_loop.html

i think your refering to this

i need to practice it more to its a hardish one to do

The dropper loop is not the knot Clown Fish is looking for.  Most baitcatchers or similar rigs that I have seen sold in shops have a single length of mono attached to the "fly" rather than a loop.  Can someone provide a link or info about this knot. 

To quote the site "Using a dropper loop is a method of attaching additional flies, baits or jigs to a single fishing line. If the loop is tied particularly large, one side of the loop can be cut where it exits the knot leaving a single strand line, upon which baits can be tied directly"

Nightwolf has it right

tie a standard dropper loop then cut one side of the loop close to the knot then your left with a single length of line. Tie you hook to that, easy.

Dropper loops are dead easy to tie, just need to be shown by someone in the know

be me, by THAT much

Have to agree with Matt, I use a dropper loop then tie a double over hand in the loop, then cut one side of that loop.

I find this not only locks the loop in, but also makes the rig stand out to the side. This helps with line not twisting as much.

Cut the dropper knot loop and then you have a single strand.  Looking at the Black Magic and Sure Catch rigs I have tho it doesn't look like a dropper knot .... ?

Thats right Alan, They are a differen't knot. I have seen them tied before, but cant remember how to tie it.

The difference is the cut line points upwards and out away from the main line.( would like to see this knot done again)

If you google that you should find it, and then it's just a matter of having the two bits of line the right way around so that the short length goes up and out from the main line.  The know is also in Geoff Wilson's book, fishing knots & rigs.