Application theme:
StyleManager.ApplicationTheme = new CrystalTheme();
Docking theme:
<telerik:RadDocking Grid.Row="2" telerik:StyleManager.Theme="Office2016">
<telerik:RadDocking.DocumentHost >
<telerik:RadSplitContainer>
<telerik:RadPaneGroup>
<telerik:RadPane Header="Description">
<TextBlock TextWrapping="Wrap" Text="On the Documents tab above press Ctrl + Mouse Left button to display the Popup Menu. You can use the same combination on every tab."/>
</telerik:RadPane>
</telerik:RadPaneGroup>
</telerik:RadSplitContainer>
</telerik:RadDocking.DocumentHost>
<telerik:RadSplitContainer InitialPosition="DockedBottom">
<telerik:RadPaneGroup>
<telerik:RadPane Header="NonDraggable">
<TextBlock TextWrapping="Wrap" Text="This pane cannot be dragged, because it has its property CanFloat set 'False'."/>
</telerik:RadPane>
</telerik:RadPaneGroup>
</telerik:RadSplitContainer>
</telerik:RadDocking>