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;
Lab, ICCBased color spaces;
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 article.
Annotations: Full support for Widget and Link annotations. All other types of annotations are supported in read-only mode.
Structured content: There are several ways to define structured content in a PDF file. RadPdfViewer does not support document outline and article threads.
When a PDF file contains some of these items, it may be shown incorrectly or not shown at all.