I use SAPNWRFC extension. But PHP tool mark this class with an unknown class warning. I have set IIS server in project property.
Sorry for the delay!
3rd party native extensions are not recognized by PHP Tools (yet). In order to workaround it, please download this file - https://raw.githubusercontent.com/gkralik/php7-sapnwrfc/master/docs/sapnwrfc.stubs.php - and place it anywhere in your PHP project.