To create a public folder calendar, you don’t need to create another account. In Public Folders, right click on All Public Folders and click on New Folder. Set the name and set it to contain Calendar Items.
Keep in mind that a public folder calendar is not going to give you the same functionality that a resource calendar will. In a resource you will have a mailbox and be able to set up scheduling rules that allow or do not allow conflicts and which will send an email back to the requestor if their time frame is not available or that their time was successfully booked. A public folder calendar does not have this functionality. If you want the features a resource calendar provides, create the user in your resources container in AD and add the word Resource on the description line after it is created. Then when someone wants to book the room they can add it as a resource. Open the resource as its own profile and set it up to auto-process the invites so that noone has to go in and manually accept and decline the bookings.