Hi mate,
If you are going to be feeding a river bank be sure to have enough of what you are going to be using. Because most of your feeding will end up in the river And if the river rises then you will loose the lot. As for feeding you can use Wheat, Barley, Potato skins, Old rotted potatos, Cereal, Bread. You should put down some feeding at the area that you are going to shoot and watch it at night to see how many ducks are going into it. Keep topping up your feeding for 2-3 weeks and keep watching the area then if there are sufficiant numbers of ducks coming in then shoot it and after youve