Will the wintergrass killer kill any rye grass growing in my kikuyu? I see it says not to use on rye grass

Unfortunately we don't have a selective herbicide for rye grass in lawn, you may try spot spray with Yates Zero Rapid 1-Hour Action Weedkiller which is a contact herbicide. Take care when applying as it will kill any plants it contacts. Click here for more info: https://www.yates.com.au/product/garden-weed-control/general-garden-weed-control/yates-zero-rapid-1-hr-action-weedkiller