how to open an Rmarkdown file in SharePoint.
I think you need to be more descriptive of what you want to do here.
R Markdown will allow you to produce output format like docx or PDF that you can share as file using sharepoint.
If you want to do something else, we need to understand, you did not really explain and give information. Your question is too wide.
Please look at the FAQ to see how to ask good question if you want more success for an answer.
Thanks, but the file rmarkdown is a file of the type dynamic because this is in really a dashboard that I have made with le package fexdashboards.
It is still only a few information that you provide. Not easy to help.
If you are using flexdashboard, it is possible that you produced HTML file (either self contained one so a single HTML, or a folder with HTML and its resources). So you want probably to publish in sharepoint the HTML results and not the Rmd file right ? Your question is not clear about that.
For HTML, you should contact any admin of your sharepoint server so know how to create a sharepoint website or networkf drive where you can serve HTML files. If this sharepoint destination is accessible with URL in browser, and you put your files there provided that you sharepoint admin allows that, then it should be enough to share the output.
This is not specific to R Markdown, it is more generic : How can you serve a static website in your sharepoint ?