In order for an inventory item to have a prescription label printed, the inventory item must be marked as "Is Dispensable." To do this, go to the Menu > Inventory > Inventory Management and edit the item. Enable the option Is Dispensable.
A box will pop up where you can enter the name that should appear on the label, DIN, strength and the expiration date of the item once it is dispensed. You can also add the default refill quantity and default prescription instructions.
How do I print a label to a DYMO label printer?
How do I configure an installed DYMO LabelWriter printer?