Thank you very much for your reply.  This particular 1120-S involves a donation of a commercial building and the value is much more than $5,000.  The Form 8283 must be signed by the appraiser and the donee organization.  Under these circumstances I believe I must attach the signed document in some fashion.  

When using the efile attachment process in Proseries, you indicate what type of form is being attached.  There are a number of special Form 8283 options, such as Art, Photo, etc.  but none of the options appears to apply to a straight forward regular Form 8283.