With Rising Storm releasing tomorrow (Thursday, May 30, 2013) the game is now available for all those who have pre-purchased (as well as all those who currently own just RO2) to pre-load. This will allow you to download the game early and start playing as soon as servers update with the released version of the game tomorrow. The SDK will also be available for pre-load the same way, which is:
Right-click on your current "Red Orchestra 2: Heroes of Stalingrad" install (or RO2 SDK install) in your Steam library.
Select "Properties" - "Betas" tab.
Use the "Select the Beta..." dropdown box - select "Preload"
"Close" - and your current RO2 (or SDK) install will update with the new Rising Storm content.
Please note - we will be closing down the beta a few hours before the release of Rising Storm tomorrow.
Good luck, have fun, see you on the battlefield!