Although, setting a global footer in IIS>Web Sites>Properties>Docuemnts is convenient, it is applied to all requests and may not be in the proper context.
It is best to include standard headers and footers from an application file, such as global.asa or in scripting. Then headers and footers will be applied only to pages parsed by the application server (ASP) and not script includes or other files where tags within the header or footer may not be in the proper context..