Thank you for your forum post.
To add a select function to a grid on the screen, please follow the below steps.
1. Open the screen in the customized tab.
2. Open the specified grid in Edit mode.
3. Go to Step 2, and in the insert column section select 'LINK' in the button. (This will place a select in the grid and let it be selected and opened.)
4. Insert the column and select FINISH.
5. Publish the page and refresh the tab it is on.
Please advise if any further information is needed.