Follow these instructions - In RM2K/3, in the bottom left hand corner, where the map names are, right click on each map and go to 'Map Properties'. At the 'Tileset' tab you will see the name of the chipset you have used for that particular map. Just put that chipset and map in the zip, and have a corresponding name for each to make it easier to sort through, and you're done.
On a side note, you should sort through your chipsets because if you have 70 chipsets then you obviously must have a few duplicates. I've mapped out almost four complete regions in Hidden Deoths and I've only used 35 chipsets, and some of them can be deleted. Just try to pick ou the best ones, with the most objects, and get rid of the rest.