If I were to bake something, and used half self rising flour, and half plain (or whole wheat, or graham or something), would I need to add more salt and baking soda to make the dough rise properly? If so, would you just add it in the same proportion as found in self rising flour?
I assume the recipe calls for self-rising flour?
If so, then yes, you can just add salt and baking powder (not baking soda). Web search says the ratio is
1 to 1½ teaspoon baking powder and a pinch to ½ teaspoon salt for each cup of plain flour.