PdfDocumentOptionsAutoResizePdfPageHeight Property

When true, the PDF page is as tall as the HTML content, so the whole content is on one page; the page width comes from the page size or, when AutoResizePdfPageWidth is true, from the browser window. The page is at least as tall as the browser window, so a small viewer height suits short content. The default value is false

public bool AutoResizePdfPageHeight { get; set; }