using (Signature signature = new Signature(sample.docx))
{
    // setup search options
    TextSearchOptions searchOptions = new TextSearchOptions()
    {
        // specify special pages to search on
        AllPages = false,
        // single page number
        PageNumber = 1,
        // specify text match type
        MatchType = TextMatchType.Exact,
        // specify text pattern to search
        Text = "John Smith",
        ShapePosition = ShapePosition.Header
    };

    // search document
    List<TextSignature> signatures = signature.Search<TextSignature>(searchOptions);

    // output signatures
    foreach (TextSignature textSignature in signatures)
    {
        if (textSignature != null)
        {
            Console.Write($"Found Text signature: {textSignature.SignatureImplementation} with text {textSignature.Text}.");
            Console.WriteLine($"Location at {textSignature.Left}-{textSignature.Top}. Size is {textSignature.Width}x{textSignature.Height}.");
        }
    }
}