Sharepoint Online search REST api – filtering news pages on select sites

Using the search api to pull content into a mobile app, what’s the right way to filter the results to get news from 2 select sites? Is there a way to use the actual site name in the filter or does it have to be the “webId”? Here’s the url I’d like to use to illustrate what I mean:'IsDocument:True AND FileExtension:aspx AND PromotedState:2'&selectproperties='Author,Path,Title,Url,CanvasContent1OWSHTML'&$filter=SiteTitle eq site1 or SiteTitle eq site2