Within Teamwork Desk, you can set a variable to include the ticket ID in a canned response.
To enable this, click your profile icon to the top right of the navigation bar and select Settings.
Go to the Inboxes subsection of the settings area and select the relevant inbox.
In the inbox details view, select Canned Responses from the left navigation pane.
You can edit an existing canned response or create a new one by selecting the green Add Canned Response option to the top right of the screen.
In the canned response modal, select the variable option from the editor toolbar.
Select Ticket - ID from the dropdown menu of variable options.
The variable will then be inserted into the body of the auto reply, you can position this anywhere within the reply area.
For more information, see: Using Variables