The FixedDocumentSinglePagePresenter is a control, included in the Telerik.Windows.Controls.FixedDocumentViewers assembly, in the Telerik.Windows.Documents.UI namespace. It is part of the source code, but you don't need its source in order to create an example like the one in the online demos.
On the other hand, when installing our controls, you should choose to install the demo applications as well. Then you will have a Demos folder just where the Binaries are installed and can run them locally on your machine.
You can find the demo application in the PDFViewer / Integration / RadBook folder.
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