I suggest you contact the hotel that is handling your reservations and ask them if there is a way that your guests can make reservations on the hotels website mentioning that they are attending your wedding. I would think that you must have gotten a special rate which you would want your guests to receive. You may even be able to add the hotel's reservation link to your website. Good luck.
if it's an actual form, see if the knot will allow you to upload the forms. most major hotel chains will let you do an online reservation through the site itself and they will give you a code to enter into the site to get the rates that you have reserved.