byte[] data = File.ReadAllBytes("verdana.ttf");
FontFamily verdanaRegularFontFamily = new FontFamily("Verdana");
FontsRepository.RegisterFont(verdanaRegularFontFamily, FontStyles.Normal, FontWeights.Normal, data);
FontsRepository.TryCreateFont(verdanaRegularFontFamily, out FontBase verdanaRegularFont);

foreach (RadFixedPage page in mergedDocument.Pages)
{
	foreach (TextFragment textFragment in page.Content.Where(c => c is TextFragment).Cast<TextFragment>())
	{
		textFragment.Font = verdanaRegularFont;
	}
}

Here is a sample structure of the signature: 

/Type /Sig
/SubFilter /adbe.x509.rsa_sha1
/Filter /Adobe.PPKMS

PdfStreamWriter stream-copy page splitting performance is much slower than expected in some cases. When working with larger PDF files, the processing time can increase a lot and cause noticeable delays.

When a document containing a SignatureField is exported with the IsEncrypted property set to true, a not set UserPassword is required to open it, which makes it impossible to be opened. An InvalidOperationException is thrown with the message "Password is not correct." when importing with PdfProcessing; Adobe Acrobat also doesn't recognize the password.

Workaround: Exporting with AES256 encryption does not have this problem:

provider.ExportSettings = new PdfExportSettings
{
	IsEncrypted = true,
	EncryptionType = EncryptionType.AES256
};

• Coons patch meshes (type 6) construct a shading from one or more color
  patches, each bounded by four cubic Bézier curves.