Answered by Shaykh Yusuf Weltch
Istilam in the Hanafi madhab is done by waving both hands and kissing them. Is this wajib? What if istilam is done without kissing the hands or just waving with one hand? Is Tawaf valid? Finally, is the round valid if you did istilam before or after the line of the Black Stone, as it is difficult to be exact on this line?
In the Name of Allah, the Most Merciful and Compassionate
Istilam (or gesturing towards the Black Stone) is an emphasized sunna action of the Tawaf. [Ibn ‘Abidin, Radd al-Muhtar]
Ideally, one would place their hands on it and kiss it if the opportunity arose without harming others. If this is not possible, or if doing so would cause harm to others, one can gesture towards the Stone from afar. [Ibid.]
Istilam is an established sunna action of the Tawaf. Not performing it does not affect the validity of the Tawaf but diminishes its reward unless one omitted it due to an excuse or forgetfulness.
Hope this helps
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani