Thank you for contacting Syncfusion support
Currently we don’t have support to place the RibbonBar at the right.But we have prepared a workaround which tries to meet your requirement. In the sample, to place the ribbon bar at the right side, we have subtracted the width of RibbonBar from the width of the ribbon and passed the calculated width as the Margin value for the left side in the Ribbon Size changed event.
Please download the sample from the below link
Please let us know if you have any concern