Using a file explorer, go to the Oxygen XML Editor [OXYGEN_DIR]/frameworks directory. Select the sdf directory and make an archive from it. Move it to another Oxygen XML Editor installation (eventually on another computer). Extract it in the [OXYGEN_DIR]/frameworks directory. Start Oxygen XML Editor and test the association as explained above.
If you create multiple document type associations and you have a complex directory structure it might be easy from the deployment point of view to use an Oxygen XML Editor All Platforms distribution. Add your framework files to it, repackage it and send it to the content authors.