Depending on the weight of the kosher salt you are using, you can generally substitute it at one cup plus two tablespoons for one cup of pickling salt, also known as canning salt. Kosher and pickling salts have no additives like iodine or anti-clumping agents, and they are a purer form of salt.
When adding kosher or pickling salt, their lack of additives keep the liquid from clouding and the foods from becoming darker. While either kosher or pickling salt can be used as a substitute for table salt, the reverse does not work. Table salt is not made in accordance to Jewish dietary laws, and its additives could affect fermentation.