If you own a Surface RT you’ll notice that by default you only get 3 rows of tiles, making it a bit limited to the amount of apps and other items you can pin in the Start screen without having to scroll-swipe to view more items.
The twist here is that there isn’t a configurable option within the operating system’s UI to add a 4th row of tiles to your Surface RT. However there is a registry tweak that it seems to be working for most users and allows you to change a specific regedit value to add one more rows to the Start screen giving you more room for apps and links.
This tweak comes from user (tamarasu) over at the XDA Developers forums and the instructions to do this are as follows:
1. While in the Windows RT desktop, launch Notepad and cut and paste these lines:
Windows Registry Editor Version 5.00
2. Now save the file “as” .reg, e.g., rtrows.reg
3. Go to the Start screen and search for regedit.exe, right-click it or short-swipe to select and from the app command, click Run as Administrator.
4. Next, from the Registry, go to the file menu, click Import. Browse the location of .reg file and click Open.
5. Finally, restart your Surface
Once you’re signed in back again into Windows, you’ll now see the fourth row and an extra 5 rows, if you go to Settings > Tiles and you turn on the option Show more tiles, while in portrait mode.
The one thing to consider is that when you do this the on-screen keyboard will appear smaller than usual, but still comfortable to use.
Source XDA Developer forums via WindowsObserver