The Windows Forms ReportPreview control automatically searches for a "dataDynamics.reports.config" file in the same directory as the application. One of the items included in this configuration file is a list of rendering extensions, also known as exports.
This file can be copied from the product install directory (located at Data Dynamics\Reports\{version}\Assemblies) and included in your project. Once this file has been added to your project, set the "Copy to Output Directory" property on the file to "Copy if newer".
Once this is done, the ReportPreview control will now display a list of exports in the toolbar.
Note: you can modify your applications copy of the datadynamics.reports.config file to limit the number of rendering extensions available to the user.