This paper presents a formula for calculating a reinsurance premium which has been determined by incorporating a lognormal-burr model into a risk-adjusted premium calculating principle called the PH-transform principle. The lognormal-burr model has been selected and validated as the best fitting model for the used insurance data among the eight candidates of composite lognormal models. The formula has then been applied in calculating reinsurance premiums for an automobile insurance branch under an excess of loss non-proportional reinsurance treaty.