In a mixing bowl, cream margarine and sugars. Add beaten egg and vanilla, mix well. Sift flour, bicarb soda and salt together. Stir into creamed mixture; blend thoroughly. Fold in chocolate chips.
Drop by teaspoon onto baking trays. Bake in oven for 6-9 minutes, depending on size. Do not overbake. Biscuits should be a little brown around the edges when taken out. Let biscuits cool for a few minutes before removing from baking tray. Finish cooling on rack.