I've looked and I don't think this is possible in Fritz 13.
It IS very easy to do using Scid vs PC. (This is why there is no "best" interface. They all have advantages and disadvantages.) What you can do is download this program, (assuming you don't already have it) and use it to search your database for the endings of your choice, and then save those games in its own database. Then exit Scid vs PC and load this new database of just these games in Fritz 13. Then you can work with it in Fritz, which you seem to prefer.
In Scid vs PC, first load the database of your choice. You probably have to do this in two different steps. The first step would be to just pull up all of the games with players rated > 2400.
THEN you would click on SEARCH and then MATERIAL - PATTERN.
Select the material pattern you're interested in. To get an idea of how to properly select the pattern on this screen, first select a few pre-set patterns in the COMMON ENDINGS drop down box, to see how the material boxes are used. (Some of the common endings all set up for you are rook vs pawns, rook vs rook, bishop vs knight, queen vs queen, etc.)
Once you're done, and you have all of the games filtered that you want, save the database as a pgn database, so that Fritz 13 can read it. (Copy (drag) them to the clipbase and then TOOLS - EXPORT ALL FILTER GAMES.
Is it possible with the game filter function in Fritz 13 to search for games containing a particular kind of endgame?
For example:
-Games with a rook ending and players elo > 2400
-Games with a pawn ending and players elo > 2400
And so on...
I know it is possible for opening by coping the position in the filter window, but I am not sure how to do something similar with endings (because I do not want to look for specific positions, just some material patterns).