The kitten starts behind a closed door
Your resident cat has owned this territory, and a kitten who simply appears in the middle of it is an intruder, however small and charming she looks to you. Begin with the kitten settled in a single room with her own tray, food, water and hiding place, and let the two cats investigate each other entirely by scent and sound under the door. Expect sniffing, listening and possibly some hissing at the door itself; all of that is information gathering, not failure. Keep this stage going until the resident cat passes the door with loose body language and ordinary interest rather than fixed staring, flattened ears or growling at the gap.
Swap scents before swapping spaces
Rub a soft cloth gently on the kitten's cheeks and let the resident cat sniff it in her own time, rewarding calm investigation with food, and do the same in reverse for the kitten. Swap bedding so each cat sleeps on the other's scent, and, once door behaviour is relaxed, let the resident cat explore the kitten's empty room while the kitten explores another part of the house. These site swaps let each cat map the newcomer's territory without a confrontation in it. Feeding both cats on opposite sides of the closed door, at a distance where both can eat calmly, builds the strongest association of all: the stranger's smell predicts dinner.
First sightings through a barrier, then brief meetings
Open the door a crack with a gate or barrier in place so the cats can see each other without reaching each other, and keep these sessions short and heavily rewarded, ending them while both are still relaxed. Then move to the same room for a few minutes, with the kitten free to retreat, the resident cat free to leave, and a person ready to interrupt calmly with a cushion or a distraction if staring hardens. Some hissing and walking away is normal negotiation; chasing, cornering, screaming or fur flying means the stage came too soon and you should return to barrier work for several more days without treating it as a setback.
Protect the resident cat's privileges
Introductions go better when the older cat loses nothing. Keep her favourite sleeping spots, feeding place and your evening lap time intact, and greet and feed her first during the transition if she is watching for her status. A resident cat who keeps her privileges has little to defend, while one who is displaced from her chair, her bowl and her owner in the same week has every reason to object to the kitten. Watch her appetite and litter habits during the introduction, because a resident cat who stops eating or starts avoiding her tray is stressed even if she never makes a sound, and that is a reason to slow the whole process down.
One staged plan the whole house follows
The commonest way introductions fail is a helper deciding the cats seem fine and letting them together unsupervised a stage early. Write down the current stage, the signals that allow moving on, and the rule that unsupervised time together waits until meetings have been calm and boring for a good stretch. KinsLe Family Sharing keeps that plan with your kitten's profile and care details, so every family member works from the same stage and the same signals rather than their own optimism.