Hello, Nelson,         

Please have a look at PdfViewerNavigator which is a great addition to RadPdfViewer. It provides predefined UI for the most common operations used with PDF files including "Page NN of TT" indication: https://docs.telerik.com/devtools/winforms/controls/pdfviewer/pdfviewernavigator

The RadPdfViewerElement.CurrentPage.PageNo gives you the number of the current page loaded in RadPdfViewer. There is not CurrentPageChanged event that can be used in this case. The page label in RadPdfViewerElement is updated when a document is loaded, scrolled to a new position or jump to a fixed page number via the page textbox in the navigator. 

However, it is definitely a reasonable request to have a CurrentPageChanged event for RadPdfViewer in the Telerik Ui for WinForms suite. 

I have logged it in our feedback portal by making this thread public. You can track its progress, subscribe for status changes and add your comments on the following link - feedback item.

I have also updated your Telerik points.

We will do our best to introduce this event in the one of the upcoming Latest Internal Builds. Currently, the possible solution is to handle the PdfViewerElement.Scroller.ScrollerUpdated event and check the PdfViewerElement.CurrentPage.PageNo property.

I hope this information helps. If you need any further assistance please don't hesitate to contact me.

Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik