When started the macro will ask you to move your mouse to the limestone icon and hit f1
After this it will ask you to move the mouse to the endurance timer icon and hit f1 again
Once you've done this you can press f1 to start the macro, it will click on the limestone icon whenever the endurance timer icon is gone and you're standing on limestone.
Please note that the macro will not work properly in combination with other timer activities, like mining and carving