public ActionResult TarifsPrint()
        { 
            return new RazorPDF.PdfResult(db.Tarifs.ToList(), "TariffsPrint");
        }        

@model IEnumerable<WEB_GIRC.Models.DirectoryTariffs>
..... ну  так далее

</tr>

@foreach (var item in Model) {
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.NumbPP)
        </td>
....

Exception Details: System.FormatException: Входная строка имела неверный формат.

Source Error: 

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace: 


[FormatException: Входная строка имела неверный формат.]
   System.Number.ParseSingle(String value, NumberStyles options, NumberFormatInfo numfmt) +398
   System.Single.Parse(String s, IFormatProvider provider) +25
   iTextSharp.text.factories.ElementFactory.GetTable(Properties attributes) +1514
   iTextSharp.text.xml.ITextHandler.HandleStartingTags(String name, Properties attributes) +2122
   iTextSharp.text.html.ITextmyHtmlHandler.StartElement(String uri, String lname, String name, Hashtable attrs) +1626
   iTextSharp.text.xml.ParserBase.Parse(XmlTextReader reader) +425

   var studentMarks = new List<DataForPDF>()
        {
           new DataForPDF()  {  a = "aaaa", b = "bbbbbbbbb", c = "cccccccccc" },
           new DataForPDF()  {  a = "aaaa2", b = "bbbbbbbbb2", c = "cccccccccc2" },
           new DataForPDF()  {  a = "aaaa3", b = "bbbbbbbbb3", c = "cccccccccc3" },
        };



            return new RazorPDF.PdfResult(studentMarks, "TariffsPrint");