Yes, set the raise hill to 1 and the smoothing tool to 1, even the smooth catmul will work shores very gently.
Then use a brush about the diameter of 2 polygons or 3 miles and quickly work the leading edge in swift strokes if it is an ocean shoreline where you have a lot of lee way to be creative. Just work the raise hill with build up or cut down until you get what you want. Sometimes the smoothing tool depending on the polymesh bias your river runs at gives better results. You can spot work it by reducing the brush to the minimum diameter, get down to nose level and slow work one tiny spot at a time. It will drive you nutz......
The beach tool does more damage than good if you are trying to keep to a theme. I've had three MA terrains to learn how to dislike that tool's results. Or you can do an illusion for rivers by setting the elevation tool to 1ft, brush in your river course, then use the path tool to lay down a river. I have 28 of those in my new terrain with bridges and roads everywhere.
