style = doc.Styles.AddStyle("TableHeader", "Normal");

TextMeasurement MeasTextTableHead = new TextMeasurement(doc.Styles["TableHeader"].Font);
TextMeasurement MeasTextTableText = new TextMeasurement(doc.Styles["TableText"].Font);

int i = 1;   
foreach (string head in table.TableHeader)
{
    paragraph = row.Cells[i].AddParagraph(head);
    paragraph.Style = "TableHeader";
    textSize = MeasTextTableHead.MeasureString(head, UnitType.Millimeter);
    row.Cells[i].Column.Width = Unit.FromMillimeter(textSize.Width+5);
    i++;
}
Unit unit;
foreach(List<string> rowData in table.TableData)
{
    row= pdfTable.AddRow();
    i = 0;
    foreach(string value in rowData)
    {
        paragraph=row.Cells[i].AddParagraph(value);
        if (i == 0)
        {
            paragraph.Style =  "TableHeader";
            textSize = MeasTextTableHead.MeasureString(value, UnitType.Millimeter);
            unit= Unit.FromMillimeter(textSize.Width + 5);
            row.Cells[i].Column.Width = (row.Cells[i].Column.Width < unit) ? unit : row.Cells[i].Column.Width;
        }
        else
        {
            paragraph.Style = "TableData";
            textSize = MeasTextTableText.MeasureString(value, UnitType.Millimeter);
            unit = Unit.FromMillimeter(textSize.Width + 5);
            row.Cells[i].Column.Width = (row.Cells[i].Column.Width < unit) ? unit : row.Cells[i].Column.Width;
        }
        i++;
    }
}