How to add spell checker in WPF RichTextBox?

RichTextBox control comes with spelling check functionality out-of-box. By setting SpellCheck.IsEnabled property to true enables spell checking in a RichTextBox. 

SpellCheck.IsEnabled="True"

You can set this in code as following:

mcRTB.SpellCheck.IsEnabled = true;

Now if you type some text, the wrong word would be underlined with red color.