The shape and size of the dish you use will determine how much topping you should add. Choose a wide shallow dish rather than a narrow, deep one for a crumble; in a deep dish there will be a little less crunchy crumble showing on top, but plenty underneath which will not become crisp. Using a shallow dish with more surface area will result in a thinner, crispy topping.
Don't worry if some of the juice from the fruit seeps through the crumble. These sticky parts taste sweet and delicious - they are one of the best bits and every crumble should have some.
** Asian Recipes