If its RMS you've got its pretty easy to change template layouts etc. In SO Manager if you go to Database -> Registers -> Receipt Templates you can see what you have currently. Look at the properties of one of them then you can read the RMS help file, and if you press properties again on one of the types you can see a preview and some limited values you can change.
However I find it easier and more flexible to edit the underlying XML files - (you can find where you store them by looking at the paths in Administrator).
They are fairly easy to pull apart and understand and modify. You have to reload them into RMS though after you change them (by clicking on the magnifying glass in the properties).
We've created delivery notes, invoices, returns notes - its all feasible (you can google and find what database parameters you can put in, a bit like Nitroscript). Bit of advice though - incremental changes are best because if you go wrong you don't get much of a clue what it doesn't like. Enjoy