Hi,
you need to modify DiscussionRadEditorToolsFile.xml file and add your custom buttons there. Take a look at the code snippet below:
<
tools
name
=
"AA"
isribbon
=
"false"
>
<
tool
name
=
"Bold"
shortcut
=
"CTRL+B"
/>
<
tool
name
=
"Italic"
shortcut
=
"CTRL+I"
/>
<
tool
name
=
"Underline"
/>
<
tool
name
=
"StrikeThrough"
/>
<
tool
separator
=
"true"
/>
<
tool
name
=
"JustifyLeft"
/>
Regards.