The M100's tool bits are seated in a small storage chamber underneath the rubber strip on the tool's outer edge, and can be accessed by pulling it open:
1) First, grab the tool in one hand.
2) Next, grip the small embossed section at the end of the rubber component and pull. DO NOT remove the part, just leverage it out until it clears the storage tube.
3) Tip the whole multitool downwards, and the screwdriver bits should slide out. A small magnet on the side of the tool will catch them halfway, stopping them from falling onto the ground.
4) Pinch the tool bit and pull it out of the multitool.
5) Close the TPU rubber component that you opened in step 2. A small tab on the base of the rubber component plugs the hole shut, and the tool bit can't fall out again.
Next, re-insert the tool bit you removed in step 4. Now that the rubber component is shut, the screwdriver bit will only go in half-way, allowing it to be used.
NOTE: As the M100 stores two tool bits inside, the second may slide forward and prevent it from closing properly. Simply point the tool hole-upwards and give it a tap, and it should fall back into the storage tube.
6) Your tool is ready to use!