Regardless of your development environment and operating system, ensure that you copy "OpenTK.dll.config" to the output directory. Without OpenTK.dll.config, your application will not function on Linux or MacOS.
1b. If you are using a fresh SVN checkout, double click "Build.exe", type "vs" and press enter twice to create OpenTK.sln. This step is not necessary if you are using a released version of OpenTK.
2a. If you are using Visual Studio, SharpDevelop or MonoDevelop, double-click OpenTK.sln, select a build configuration (debug/release) and build the project.
2b. If you wish to build from the commandline:
[Windows]
Make sure msbuild is in your path and type:
cd Build
Build.exe vs
msbuild
[Linux / MacOS]
Make sure nant (http://nant.sourceforge.net) is in your path and type:
cd Build/
mono Build.exe nant release
4. The resulting binaries are placed into the Binaries/Release or Binaries/Debug folder.