BATH & BODY PRODUCTS: 1-3% is considered the general "skin safe" ratio for lotions, creams, bath salts, fizzies, scrubs, body butter, salves, shampoo, conditioner, body spray, shower gel, etc.
COLD PROCESS (CP) SOAP: 0.7 - 1 oz per lb. Delicate florals should be batched at cool temps.
If a fragrance doesn't note it's compatible in HP, is it? Typically, if it's CP compatible, then yes, it's HP compatible. Usually, the exception is fragile florals (jasmine, gardenias, etc) and essential oils. Add fragrance oils last, after the cook phase or at trace and right before pouring into mold...this way there is less evaporation from the prolonged heat. However, you must stir this rather thick mixture very thoroughly.(For both Hot process in the oven, in a pot, or in a crockpot).
FIXING A SEIZE! Hot-Process is a great way to fix a CP seize in the pot.
Hot processing on the stove or in a double boiler setup to save a seized batch. You will typically need to add an extra ounce of water per lb of soap to make it easier to stir and to smooth into your mold, but this is an excellent way to fix a batch that has seized. You don't want to "cook" the bottom of your pot, so keep heat very low or use a double boiler to ensure your soap doesn't burn. Add your extra water and heat; it will go into the gel phase fairly quickly and only needs to "cook" a little longer to make pouring into the mold easier. It will not be liquid like CP soap, but it should be made fluid enough to smooth into a mold without lumps and air bubbles. Patience here is the key, as you will need to cure as long as with CP simply to allow the extra water to evaporate fully. You may choose to use less water to get a harder bar faster, BUT this will result in a thicker "glob" of soap that will be difficult to smooth into your mold, so the final texture of your soap may suffer.
MELT & POUR (MP) SOAP: 1 TBS per lb, up to .5 oz per lb or 1-3%
PARAFFIN WAX: 1 oz per lb. (Average usage of fragrance oil is approx. 6 - 7% per lb.)
SOY WAX: 1 oz per lb. unless otherwise noted
Note: The above are general guidelines. Individual testing and formulating is necessary