No you can't put two font parameters in one drawstring.
What you can do is create a custom method which takes in value to print as one parameter
so the call would be like
yourCustomMethod(txtBox14.Text);
and your method could be like
void yourCustomMethod(string str)
{
e.Graphics.DrawString(str, new Font("Arial", 11, FontStyle.Bold), Brushes.Black, 790, Ypos, new StringFormat(StringFormatFlags.DirectionRightToLeft));
e.Graphics.DrawString("`", new Font("Rupee Foradian", 11, FontStyle.Bold), Brushes.Black, 730, Ypos);
}