Our prototype SMT stencil size will be 1 inch bigger(1 inch from Top, bottom, left and right) than your board size.
If you have special requirements for your stencil order, please put the notes in the Comments section. Your PCB board: will be position in the center of the stencil by default, if you want it to be off center, please also put the instruction in the Comments section.
Here is the link for how to use PCB Prototype Stencils: