To assign supplement plans to a client, use this + button on the right edge of any day from where you want to assign the plan. Click on Supplements

It will open the supplement plan selector. You can specify a single supplement plan for all days. Optionally assign supplements tailored for rest days to support recovery and overall health.

NOTE: If you assign a supplement plan for rest days, the daily supplement will refer to the training days. This way, you will assign supplements for training and rest days separately.