are there any engineers that could possibly help me with a calculation.

I have a keystone HD/K 50 lintel 3.3m long and an RSJ that sits on it. Keystone have told me that worst case scenario (centre point) the lintel will take a 5-10 KN point load. My RSJ sits just off the 150mm lintel pier. Therefore it can obviously take a bigger point load than if it were in the centre so i know it's safe. Where the RSJ sits on the lintel R= 2.25 KN so it's well within limits but my building inspector wants something written from keystone (which they wont do) or a calculation.

Does anybody know how to calculate it...?

Keystone HD/K 50 3.3m long

Height 209mm
Thickness 3.2mm

Total UDL in Kn 3:1: 35

Total UDL Kn 19:1: 32

ixx: 1099.84 cm4
zxx: 77.01 cm3

Cheers