Scroll down to the section labeled Entity Attributes. The section will look something like this:
Check the box under the Assert Column for the row labeled REFEDS Research and Scholarship Support:
You will be asked if this is something you really want to do. Click OK once you verify that you have not unchecked any other entity attributes you did want to assert and have not accidentally checked any other entity attributes.
Verify at the bottom of the page that your IdP's metadata is now asserting R&S like below. Blue text will indicate additions to your metadata while strikethrough text will indicate deletions from the metadata.
In this case, Hide from Discovery was also added. If you did not expect Hide From Discovery to be added, scroll back up to the Entity Attributes section and verify that Hide from Discovery was not accidentally checked when R&S Support was added.
Once you have verified that everything looks good, click on Submit Changes near the top of the page. Your metadata will be automatically approved and published within one business day.