To add a flavor oil or essential oil: Just melt in your microwave on low, stir, add essential oil or flavor oil, stir again and pour into your lip balm tubes or pots. Then let them cool before use.
Essential Oil or Flavor Oil can be added between .5% and 2%. This trick might help make the math easier; for 1% add 5 drops of essential oil to every 1 ounce of product.