How to Add a Form to an Activity:
You can assign any form to an activity. By clicking on the activity, it will open the activity details.
There you will see a Forms Box. Clicking on this will show the Forms list which are available for you and you can select any of the form from the drop down.
Once the form is added to the activity it will show like this...
Click the Save button at the bottom and the form is not attached to the activity.