In my opinion,
F = Delta_P x Ai x DLF.
What the surge report gives you is maximum surge pressure (or peak pressure) P in chart result. And P0 is steady state pressure (or operating pressure) which is available from line list or can be read from chart at Time O seconds
Delta_P (maximum unbalanced surge pressure) can be taken from chart result (by using formula Delta_P = P - P0) or detail discussion with process.
If using P = P0 + Delta_P for calculating F will give you a very big value which leads to unnecessary over design of pipe support or pipe over stress
Looking for other opinions