PdfPageWord Class

static void Main(string[] args)
{
    HashSet<string> FontNames = new HashSet<string>();

    using (PdfDocumentProcessor processor = new PdfDocumentProcessor())
    {
        processor.LoadDocument("Document.pdf");

        //Check all words in the document
        PdfWord currentWord = processor.NextWord();
        while (currentWord != null)
        {
            //Add the current font name to the list
            for (int i = 0; i < currentWord.Characters.Count; i++)
            {
                    FontNames.Add(currentWord.Characters[i].Font.FontName);
            }
            currentWord = processor.NextWord();
        }
    }
    Console.WriteLine(string.Format("The loaded document contains the following fonts:\r\n{0}", 
    string.Join("\r\n", FontNames.ToArray())));
}

Private Shared Sub Main(ByVal args As String())
    Dim FontNames As HashSet(Of String) = New HashSet(Of String)()

    Using processor As PdfDocumentProcessor = New PdfDocumentProcessor()
        processor.LoadDocument("Document.pdf")
        Dim currentWord As PdfWord = processor.NextWord()

        While currentWord IsNot Nothing

            For i As Integer = 0 To currentWord.Characters.Count - 1
                FontNames.Add(currentWord.Characters(i).Font.FontName)
            Next

            currentWord = processor.NextWord()
        End While
    End Using

    Console.WriteLine(String.Format("The loaded document contains the following fonts:" & vbCrLf & "{0}", String.Join(vbCrLf, FontNames.ToArray())))
End Sub