harmon.ie allows you to filter search results using SharePoint result sources (search scope rules in SharePoint 2010). Result sources are defined in the SharePoint administration Manage Result Sources page.
When adding one or more custom result sources, harmon.ie automatically adds a new search scope as well – Search All Content. If this scope is selected, no result source is used.
To invoke a custom search, user has to select both the search location (search This Library: <name>, This Site: <name>, or All Locations of Site: <name>) and the search scope (preconfigured or Search All Content).
Limitation: When working with SharePoint 2010, harmon.ie only supports search scope rules of type Property Query.
Add the SearchScopeList registry keys, as explained in: