Click on the Draw tool and select T mark.
Place your cursor and single click where you would like to start the T mark, then drag your cursor to create the T. Single click to finish then either add additional T marks or click on Finish.
With the T mark selected you can change the sizing or rotation by dragging as needed. You can additionally change the styling by clicking on the Style button when a T mark is selected.
From here you can change the width, opacity, style and colour