Multi-textured terrain XNA-monogame

I’m developing a TerrainEngine for my project and I have some issues with the multi-texturing part.

I already tried some techniques but it doesn’t match with my TerrainEngine’s conception.

My TerrainEngine is made using the concept of Regions, Sectors and tiles.

• A region contains 16×16 sectors
• A sector contains 8×8 tiles
• A tile contains all informations like 4 height points, 4 textures (one on each corner)

So I can create a terrain of 5×5 regions if I want to. But that’s not the point.

My question is, how can I proceed to make an efficient multi-texturing using the RST technique and using XNA/Monogame ?

I’ve heard about a technique named “Texture Atlas” but I don’t no if that’s a good option.
What did you suggest ?

Oh, and I’m using 4 texture samplers in my HLSL.