To install Kali on Raspberry Pi, follow these steps:

1. We will first download the Kali Linux image from Offensive Security's website at https://www.offensive-security.com/kali-linux-arm-images/:

2. Once the image is downloaded, we can use different ways to write this image into our memory card.
3. On Linux and macOS, it can be done using the dd utility. The dd utility can be used using the following command:

dd if=/path/to/kali-2.1.2-rpi.img of=/dev/sdcard/path bs=512k  

4. Once this process completes, we can plug the SD card into the Pi and power it on.
5. We will see our Kali boot up, as follows: