This is a very popular form of fishing and the example shown with the bulk shot close to the float is probably close to the top of the list. Place a single shot about 6 to 10 inches from the hook to assist in bite detection, do not hesitate to alter the position of this shot or the rig if bites are hard to hit. A good way to start is to have the bait either on or just off the bottom.
Shortening the rig as necessary to find the fish. Remember the shallower you fish the harder it tends to be to hit the fish. If you find you are continually getting bites on the drop then alter the shot pattern accordingly to make the bait sink faster. That is of course unless you want to target those fish in the upper reaches. Re spacing of the shot may also help if there is a strong under tow on the water. Use as finer tipped float as the weather will permit. The bites will be more positive.