As I am not exactly sure about the requested functionality, I will suggest two approaches that most probably will help you with your scenario.
In case you have a RadRotator on your page and you want to display more than one item in the control's ViewPort, you can do so by synchronizing the Width and ItemWidth properties, according to this help article. The First Look online demo of the RadRotator implements such scenario, so you can use it as a reference.
If you have a RadSlider and a RadRotator on your page and you want to control the sliding of the of the rotator's items with the slider control, you can achieve such functionality by utilizing the rich Client API and events of the mentioned RadControls. For your convenience I have attached a sample project, implementing the described feature. You can use it as a base for your further development.
If the already presented solutions doesn't cover your case, please describe in greater detail the scenario you want to achieve, so that we can suggest the most appropriate solution.
Kind regards,
Slav
the Telerik team
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