Ranorex is not supported out of the box with Silk Central so you will likely need to create your own plugin for this. The best place to start would be to check out the Silk Central API Guide which shows how to create custom plugins and provides some examples. This can be found here.
if triggering the exe file is needed for executing the test then it will do so. As Michael already indicated there is no out-of-the-box integration with Ranorex - hence you have write your own plug-in for it (see link above).
And in this plug-in implementation you can do what every you need to do to run your scripts and process your results.