Hi Peter,
To add a rain delay, you can go to the Schedule page of the app, press the + sign on the right upper corner and select Rain Delay. If you want to review the created rain delays, you can go Settings->Restrictions and your the rain delays will be shown. You can edit and delete the existing rain delays too. Please refer to this forum article
https://www.netrohome.com/forum/posts/282/show_question
Thanks,
Netro Support