At the beginning of the Profile Section of your return;
Online users - The first question asked - Did you work in 2018? Yes - Check - I was employed - Check - T4 - Check - I worked in Québec and received a Relevé 1 slip
For those using the downloaded version, the first question you answer about "working" will open the dropdown and you will see the option to check RL-1.
If needed see below:
What do I do if I have a T4 slip with no matching RL-1 slip or an RL-1 slip with no matching T4? - https://bit.ly/2Smoqmn