I finally understand that you want to use R conda environment with RStudio. reticulate is not for this.
Usually, I have seen R and Anaconda used together on Desktop, and Anaconda Navigator allow that:
https://docs.anaconda.com/anaconda/navigator/tutorials/create-r-environment
For doing it without navigator, did you try to configure RStudio to use the R version in the conda env you want with RSTUDIO_WHICH_R ?
See linux part, in this doc
There is an example you can adapt
I am not sure it works, however, it worth the try I think.