Rmarkdown: Error in py_module_import : No module named 'rpytools'

Apologies this is a crosspost from stack overflow as I got no reply there.

I am trying to add a python chunk in a rmarkdown document. I installed package reticulate then here is my document:

```{r, message=FALSE, warning=FALSE, echo = FALSE}
  library(reticulate)
```

```{python, echo = FALSE, eval = FALSE}
a=1
a
#import numpy as np
#import matplotlib.pyplot as plt

## evenly sampled time at 200ms intervals
#t = np.arange(0., 5., 0.2)

## red dashes, blue squares and green triangles
#plt.plot(t, t, 'r--', t, t**2, 'bs', t, t**3, 'g^')
#plt.show()
```

However I get this error when knitting the document: (note that the error happens when running the second chunk)

label: unnamed-chunk-1 (with options) 
List of 3
 $ message: logi FALSE
 $ warning: logi FALSE
 $ echo   : logi FALSE


  |                                                                       
  |....                                                             |   6%
  ordinary text without R code


  |                                                                       
  |......                                                           |   9%
label: unnamed-chunk-2 (with options) 
List of 3
 $ echo  : logi FALSE
 $ eval  : logi FALSE
 $ engine: chr "python"

Error in py_module_import(module, convert = convert) : 
  ModuleNotFoundError: No module named 'rpytools'
Calls: <Anonymous> ... remap_output_streams -> import -> py_module_import -> .Call

Also adding that I did not find any information on this on https://github.com/rstudio/reticulate
and
https://rstudio.github.io/reticulate/articles/r_markdown.html

I have knitr version 1.20, which is above 1.18 hence engine configuration should be automatic.

I also precise python3 is present in the windows PATH.

Reproduce the reported R Markdown document with reticulate on Windows, focusing on the second {python} chunk and the py_module_import/remap_output_streams stack. Check the installed Python environment and reticulate/knitr versions against the documented R Markdown setup. Done when the chunk knits without the missing-module error or the required environment configuration is documented.