What is the correct procedure for incorporating salicylic acid into a corticosteroid-containing ointment consisting of 0.05% clobetasol dipropionate, 30 g TMF hydrophobic ointment, 40 g Unguentum simplex, 10 g talc, 10 g zinc oxide, 2 g salicylic acid, and aqua dist. q.s., given that the physician specified adding water until saturation when asked about the total volume?