You can list all your donations. Turbotax will create the necessary forms. Extra signatures are not required on those forms unless the value of a donation of a single item or "group of similar items" is more than $5000.
A suggestion for the future though -- take your itemized list to the charity and have someone sign your list along with giving you a receipt, to show that what is on your list actually matches what was donated. There are some reports of IRS auditors requiring this, even though it is not stated specifically in publication 526.
