Hello, Monique,

Thank you for writing.

I would like to note that layers are not yet supported in RadPdfViewer. We have logged an item about it: ADD. RadPdfViewer - add support for layers (optional content) (telerik.com). You can cast your vote for this item to increase its priority. 

If I understand correctly your request, you would like to introduce API in RadPdfViewer that indicates whether a document has layers (such as HasLayers property). I find this a reasonable request and I approved it on our feedback portal. However, keep in mind that the availability of this future property depends on existing support for layers and may be planned subsequently. Adding support for layers is a significant feature that will be revised with priority.

I hope this information is useful. Let me know if you have other questions. 

Regards,
Nadya | Tech Support Engineer
Progress Telerik