It would be really more usable to add keywords or complete smart folder details through an external file.
when you have dozen terms you want to test match against a rss text, it's really boring to enter them one by one.
1- add an import and export text file for keywords for a corresponding operating
2- import/export capability for complete match google style
date:1999 intitle:vienna author:mike text1 text2 ...
3- when adding line, keep previously used operator and matched fields
4- add a matched fields: subject and text or all article.