To prevent break out, it is essential to back up the cut on both sides. One side is supported by a back fence screwed and glued to the template and the front is supported by another scrap of wood which is simply held in place as the strip is cut. Finger pressure is sufficient but obviously keep your hands away from the cutter. In this shot, I am holding the bearing cutter to illustrate how the whole system works. Of course normally the cutter would be held in an inverted router on a table.
Use a sharp carbide tipped cutter; teak is very abrasive and will dull a HSS cutter in no time at all.