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[blackboard]

I played Discworld a few days ago using Dosbox 0.71 and Rincewinds inventory worked fine. Did you enlarge the inventory window? (Pull the borders) Otherwise it might get full with the pouch and the pick-pockets icon.
You should be able to simply drop objects into the window with a left click.

The only other problem I can think of is that Rincewind can only carry limited number of objects (I think two), so if its inventory is full you might have to move something into the chest.