If you are vegetarian, check the ingredients on your cheese to ensure there is no rennet, which is derived from animals. Parmigiano Reggiano (the authentic Italian version) uses rennet. Many of the versions of the cheese produced in other countries use microbial or bacterial enzymes in the cheese-making process rather than rennet.
The cheese in the crisps should have enough salt so that you do not need to add additional salt to the recipe. If you prefer a saltier crisp, sprinkle lightly with salt before baking.