To make yeast dough, stir 1 teaspoon sugar into warm milk and sprinkle with yeast.
Let stand 5 minutes or until the surface is frothy.
Stir gently to moisten any dry particles remaining on top.
Sift flour and salt into a large bowl.
Melt margarine; cool slightly.
Beat margarine, remaining sugar, eggs and almonds in a medium bowl until frothy.
Stir in yeast mixture; add to flour mixture, combining to make a soft dough.
Cover and let rise in a warm place 20 minutes.
Knead dough well on a floured surface.
Divide into golf-ball size pieces; shape into balls.
Make a hole in the middle of each ball with the handle of a wooden spoon.
Twist spoon to form doughnuts into rings.
Let rise in a warm place 15 minutes.
Heat oil for frying to 360°F (180°C) in a deep-frying pan.
Place risen doughnuts four at a time in hot oil; fry on both sides until crisp and golden.
Drain on paper towels; cool.
To make frosting, combine egg white, powdered sugar and rum in a small bowl.
Spoon frosting over cooled doughnuts; sprinkle with sliced almonds while frosting is soft.