Remove the soffit panels from the underside of your eaves where you install your soffit vents. Measure the length and width of your soffit vents and mark each soffit panel before cutting. Measure the distance from the edges of the soffit panel to Mark the places for the cuts so the soffit vent sits between the rafters above the soffit panel.
Cut each panel with a router so the soffit vents fit snugly in the holes in the soffit panel. Using exterior-grade wood screws, fasten a soffit vent to each panel. After the vents are installed you can replace the soffit panels in their original positions.
Place an insulation baffle on the underside of the roof deck above each of your newly installed soffit vents. Secure each insulation baffle to the roofing deck with the staple gun. The ends of the baffle should extend well above your insulation and below it towards the soffit vent.
Place additional batt insulation around the soffit baffle to ensure that heat does not leak through the ceiling near your exterior walls. Make sure that this insulation does not cover the soffit vent or the end of the insulation baffle.