You could try a 1/2 , see if you like it .So a half inch cove bit would be fine? Is your jig adjustable? Any pics of how you made it? And tips? Thanks
I just use a simple " T " profile .

One longer horizontal side screws to work bench ,
The short side is cut to set the distance from side of the board to the groove , also holds the board in place .

The vertical acts as the fence to guide the router .

screws around all 4 sides . I make 2 long sides , 2 shorts for the ends .

Size of the cutting board , and the router you plan to use will give you your numbers .