How to embed a shiny application into an Rmarkdown html document

Question

I would like to create an html document with RMarkdown, containing text, Rcode and somewhere in between a shiny application.

I thought of using asis=TRUE for the shinyApp(ui, server) block, but RStudio only renders the Rmd file, if I add runtime: shiny to the YAML-Header.
If I do so, no html is created, but I can move to browser view.
If I look at the source code in the browser view , I still don't see the entire html code.
If I check the generated temporary file, I was not able to find the html file representing the entire RMarkdown document.

How to generate html-code from the shinyApp function? Or: How to generate an html file, from RMarkdown containing a shiny app instead of e.g. a plot

I hope you have some idea for me.