The font size when you print is determined by the size of the tree you are trying to print, the size of the paper you are printing on, and the number of pages you are printing to (height and width). Family Echo will make the font small enough to fit your tree onto the size you select.
I find Family Echo to be a wonderful tool for maintaining my family tree, but when I need to print it, I export my tree and print it from a program like Family Tree Maker. There are also services that will print your family tree for you however you like from your GEDCOM file.
