As of now RadEditor for SharePoint 2013 or sharepoint 2016 is not available, reason Telerik had provided for non-availablity of RadEditor for List Items as it is handled from client end is not acceptable, since many other component providers do support similar functions with their editors. the reason / use case iam looking for is becoz of need to handle clipboard manager in editor which is not available in Multiple line of text column type of an SharePoint 2013 list,
For client-side scenarios we recommend using the Kendo UI framework as explained in the following blog posts: https://www.telerik.com/blogs/using-kendo-ui-in-sharepoint-online-how-to-series https://developer.telerik.com/featured/introduction-using-kendo-ui-sharepoint-online-series/