After the rabbet has been cut in the back of the panel, it's time to begin making the cove cuts on the front of the panel. You'll want to make a few test cuts before beginning to cut the face of your panels to make sure that you have the shape you want.
Begin by removing your dado blade set from your table saw and replacing it with a clean, sharp saw blade. Do not re-install the riving knife or saw blade guard.
As you're completing the blade's installation, make a pencil mark on your throat plate that denotes the center point of the arbor of your saw when the blade is completely recessed beneath the table (remember that your saw blade is likely not raised in a straight line, but along the path of an arc, so the center point when the blade is raised all the way will be different than when the blade is recessed).
Next, clamp a 2x4 onto the top of your table at a 45-degree angle to the path of the blade, with the edge facing your body crossing at the pencil mark you made on the throat plate. This 2x4 will serve as the fence for making your cove cuts, so be sure that it is clamped securely and that the clamps will not interfere with the panel as it is being cut.
Time for a test cut. With the blade still recessed, turn on the table saw and raise the blade about 1/8" above the table surface (cutting into the 2x4 fence slightly). Then, place a scrap piece of stock with the face flat on the table and the long edge against the temporary fence, and push the board across the blade. This will create a shallow cove shape in the board.
Raise the blade slightly, and cut the cove again. Continue this process until you are satisfied with the shape of the cove in the test board.
SAFETY TIP: Remember that you're working with an exposed saw blade, so be certain to keep your hands well clear of the blade as you're cutting.