Two suggestions: The scarf should be at least 10:1 or better 12:1. It should run vertically, not horizontally, through the toe rail. (If you look at the cap rail of a traditional
boat, the scarf runs horizontal to the
boat, but vertical to the wood grain, because the cap rail is laid flat on top of the bulwark.)
Ideally a spline would be installed blind inside the scarf joint due to the curvature induced at
installation. That means that the scarf joint(s) would be made on the bench, then the whole toe rail bent to the sheer as one piece.
The best glue is Resorcinol for teak timber, i.e. not veneer, that will be exposed to moisture and therefore expansion and contraction - which is not Wood Epoxy Saturation Technique encapsulated. See the Gougeon
manuals on wood expansion and epoxy.
If you must use epoxy, do not use teak dust as a filler. Reasons above are correct. Use moderate to low clamping pressure to ensure that the epoxy is not squeezed out of the joint. When using Resorcinal, use lots of glue and very high clamping pressure. This forces the glue into the wood grain, making a stronger joint.
Practice, practice, practice. Destruction test the practice pieces. Observe where and how the joint fails. That's the fun part.