string fileName = "file.xlsm"; 
            Telerik.Windows.Documents.Spreadsheet.Model.Workbook workbook;
            IWorkbookFormatProvider formatProvider = new Telerik.Windows.Documents.Spreadsheet.FormatProviders.OpenXml.Xlsm.XlsmFormatProvider();

            using (Stream input = new FileStream(fileName, FileMode.Open))
            {
                workbook = formatProvider.Import(input);
            }