DD - I have a top loader and mine goes into the agitator cap bit - so I lift it up to put the detergent in there - and then add the rinse to the top of it, where the softener would go. Dunno if yours has a hole in it like mine or if it is capped? I had a capped one before, and the washing machine had a little tray at the back that flipped out, washing liquid on one side, fabric softener on the other - so I put it in the fabric softener bit.

Oh, and I just add it at the beginning of the wash. Less trips to the laundry that way.

Oh, and I use about a lid full (the canestan lid)