Dear Li,
in the Norm field you should enter the area, FLUKA will divide the result by that number. You can check that on top of the *_sum.lis file.
Mind that the output is a yield per solid angle (which is defined using the polar angles) so the bin width is not constant. From the *_tab.lis file you can use the first and second column which are the polar angles defining respectively the lower and upper values of the solid angles (with the relation 2π(1-cosθ)). The width of the solid angle bin will be2π(cosθ1 - cosθ2). If you are not convinced you can also calculate the cumulative yield and then check that what you get is consistent with what is written in the *_sum.lis file.
Best,
Davide