Outlook | Signature Designer

Steps

In Email Signature Designer : Install > Copy to clipboard ;
Open Microsoft Outlook app ;
Open Preferences… panel ;
Select the Signatures icon ;
+ to add a signature ;
The edition window should appears, you can define a Signature Name ;
Paste the signature in the text area with the keyboard shortcut cmd+V ;
Save the signature ;
In the above section, you can set Choose default signature: to automatically pre-fill the signature when writing a new message.

You can now compose a message with your new signature.