Hi @jcblum - thank you very much for your prompt reply. I think I have a misconception of how to use packrat then. Let's say I want to create a new package using rstudio. I start a new project, select rpackage as project type, and check the packrat tick box. rstudio then creates the files and folders:
- DESCRIPTION
- man
- myNewProject.Rproj
- NAMESPACE
- packrat
- R
So the packrat folder is located in the directory that contains files and folders relevant to my new package. Now, you mentioned that the packrat folder should not be part of my new package, may I just move it elsewhere then? Thank you very much for your help. You can tell this is my first package. 
Cheers, Christian