Stencil Usage with a RenderTexture

I'm trying to render into a separate custom RenderTexture using Graphics.Blit(...) calls in order to build up a texture that I'm using later on in rendering.
I also use Graphics.SetRenderTarget(colorDest, stencilDest) in some cases when setting my render target(s) and manually draw the full screen quad.

I don't seem to have access to the stencil buffer for this RenderTexture for normal stencil testing on DX9.
In DX11, my rendering set up works just fine.

I set up my RenderTexture with the following code:

Code (CSharp):

1. rt = new RenderTexture(xdim, ydim, 24, RenderTextureFormat.Depth, RenderTextureReadWrite.Default);

Is there a different way I'm supposed to set up RenderTextures or set them when I want to use a custom RenderTexture stencil?

Thanks!