The unsupported features include:
Almost all fonts that are embedded in the PDF file should be displayed correctly. There are minimal limitations with some font formats.
There are some limitations with CCITTFaxDecode filter.
Encrypted documents when a non-standard encryption method is used, or the document is password-protected.
JPXDecode filter: This filter does not work out of the box. However, there is API allowing to plug-in custom user-defined filters. This API is described in the Customize PDF Rendering topic and an SDK example showing the approach is available in our SDK repository on GitHub.
Annotations: Of all annotations, only link is supported.
Structured content: There are several ways to define structured content in a PDF file. RadPdfViewer does not support document outline and article threads. The interactive forms are currently read-only.
When a PDF file contains some of these items, it may be shown incorrectly or not shown at all.