How Much Benzocaine 20% Should I Use On Skin To Have The Same Absorption Effect As In Applying It To Mucous Membranes?

I should give more info: There is this "no scream cream" for brazilian or bikini waxing. It is 20% benzocaine gel. When I went to the dentist, I believe they used the same benzocaine concentration to numb my gum before the anesthetic injection. I want to use it safely, and there are no dosage instructions on the label. Since the skin does not absorb as much as the mucous membrane, I was wondering if I should use 2 swabs ...or just one like on mucous membranes and wait longer for the absorbtion.

Thank-you,
adriana