The 49ers placed Kirk (knee) on injured reserve Saturday.
Kirk made his season debut in San Francisco's last game in Week 7 in Atlanta, going without a target on a 30 percent snap share. After a Week 8 bye, he showed up in the initial Week 9 practice report Wednesday as limited due to a knee injury, which head coach Kyle Shanahan revealed to be to the wide receiver's meniscus Friday, per David Lombardi of SFStandard.com. Shanahan also relayed that Robinson may need surgery, but at the very least he'll miss the team's next four contests.