You can add Kiri widgets the same way you add other iPhone widgets, then place them where they are easiest to reach during your day.
Add a Home Screen widget
Touch and hold the Home Screen until apps begin to jiggle.
Tap the + button.
Search for Kiri.
Choose the widget size you want and add it.
Place it where you want and tap Done.
Add a Lock Screen widget
On supported iPhone versions, edit your Lock Screen, choose the widget area, and add Kiri if it is available there for your setup.