What do you add to cake flour make it self rising flour?

To make self-rising flour, you will need to add baking powder and salt to cake flour. The general rule of thumb is to add 1 1/2 teaspoons of baking powder and 1/2 teaspoon of salt for every cup of cake flour. Be sure to whisk the ingredients together thoroughly to ensure even distribution. Once combined, you can use the self-rising flour in any recipe that calls for it.