You need to run the following
$ source ~/.rvm/scripts/rvm
then run this
$ type rvm | head -n 1
and if you get
rvm is a function
the problem is solved.
You also need to run user$ rvm requirements
to see dependency requirements for your operating system
Source: https://rvm.io/rvm/install/
I forget mention that you need to put this code into you ~/.bashrc or ~/.zshrc file and you will not need to write this code again. Cheers!