According to the card, for a bath 4–7 drops of the oil are added to water at a temperature of 37–40 °C. The card does not specify the length of the bath or whether the oil needs to be mixed with a base first. The oil is for external use only; avoid contact with the eyes and mucous membranes.
General information (not a manufacturer's instruction): essential oils do not dissolve in water, so they are often mixed with a base first; if the skin becomes irritated, stop the bath and see a doctor.