After you create a PDF of the tax return, by following the instructions that DoninGA gave you above, open the PDF in Acrobat Reader (or any PDF reader). The Print function in Acrobat Reader will let you select the pages that you want to print, so you can print just the signature page.
But why are you looking for the signature page? The signature page in the PDF of your tax return will not have a signature on it. Is someone asking you for a copy of your tax return with your signature? If you e-filed there is no written signature. An e-filed tax return is signed electronically when you e-file it. Probably the simplest solution is to print a copy of the tax return (or just the signature page, if that's what you're being asked for), sign it with a pen, and give the signed copy to whoever is asking for it.
