Here are a couple youtube vids showing how it works.
Im using about 400ml of a seasol like liquid fertilizer in a 1.25L bottle for 40 plants.
Step 1: Add Conections to the Bottle.
Drill tight holes in the lid and glue them in.
Add a short and long piece of hose to the inside.
Step 2: Add Conections to Your Irrigation System
Add a tap with enough room either side to insert small barbed connectors.
Insert barbed connectors either side of the tap you put in.
Put a loop of thin hose on the barbed connectors.
Step 3: Connect the Bottle
The other hose on the garden side goes to the bottle barbed connector with the short hose inside.
Step 4: Try It, Calibrate the Flow.
To do this the tap you put in should be turned slightly so it creates a pressure difference and creates flow through the bottle from bottom to top.
The photo of the diluted mix in the bottle was after running for 20mins. I was happy with that delivery rate.
Remember to use a pressure reducer as recomended for dripper systems so your bottle will hold up ok.