Articles fully implements the ISearchable interface so it should work properly with the global search and RSS feeds built into DNN. If you are having a problem, the first thing you should try is clearing the search tables and re-indexing the content. To do this:
1.) Login as host or another superuser account
2.) Go to the Host->SQL tab and run the following as script:
3.) Go to Host -> Search Admin and click the Re-Index content button. It may take awhile for the re-indexing to complete so give it a few hours before testing again.
If this does not work, there may be another module that is causing issues with Search. Look at your Event Viewer and see if you can find any error messages relating to search.