No. You, as well as your guests that you have over too, also have access to the common areas of your house. You don't charge them to visit you do you? 🙂
The rental portion percentage is that floor space that is "EXCLUSIVE" to the renter, and nobody else including you for your personal use. So if your 2nd bath is only accessible by walking through the renter's bedroom, then that bath is exclusive to the renter, provided it can not be accessed from any other room.
But if that 2nd bath is across the hallway from the renter's bedroom, then that bath is a common area and is not exclusive to the renter. Most likely guests that you may have over also use that common bath. so again, it's not exclusive to the renter. (Unless you put a lock on it, and provide the tenant a key so only they can access it.) You can not include it in the floor space percentage that is exclusive to the renter.
