Is falling into the posture of prostration when kissing a father's foot or placing one's head upon it, without the intention of prostration, considered shirk (associating partners with God)?

It is permissible to kiss the foot of one's father out of love and respect for him. The Companions did this with the Prophet, peace and blessings be upon him, which indicates its permissibility, as delaying clarification beyond the time of need is not permissible.