Step 1. Create a plane object with the settings shown (make this object editable)
Step 2. Then hit the Content Browser, in the Interaction folder, select TP Move on surface
Step 3. Select TP Move on surface in Objects manager then drag the plane object into the surface object field
Step 4. Back to the Content Browser, select TP Standard Emitter (in the Emitter folder) and TP Planar gravity (in the Effectors folder)
Step 5. Now lets make some bubbles. Create a small sphere object then select TP Standard Emitter in the objects manager, drag the sphere object into the shape field, change the TP Standard Emitter settings as shown
Step 7. To make the bubbles vary in size I added user data (size variation) in the TP Standard Emitter to modify only the scale. Learn how to Add user data with Xpresso here
Step 8. Play the animation, you can do experiment for the plane object, give the ripple effect or deforming this object and look at the bubbles move on the surface ( to get some good effects, in the below i used
a good hdri enviroment for reflections and water shader)