Draw diagonal line in the report

I would like to draw diagonal line starting from RHS toward downside to LHS -
the height should be the difference from the point where the detail section
ends and the pagefooter starts.

Actually I am preparing a report for delivery note, where the following
heights are the
Report Header
Groupsection/level - only one
Detail section - which expands or retracts according to number to records
Pagerfooter - where the total fields is there

Now I have been asked to draw a line diagoonaly (from the RHS side to LHS -
towards downward) starting from the point where the detail section ends and
it should end exactly where the pagefooter starts. Just to show that there is
nothing inbetween these spaces.

I tried but failed as the the detail section data for all record is not same.

Pleas advise.

Regards.

Irshad