Dear Jayaram,
When it comes to paying PF for laborers, you need to upload the returns on the PF site like everyone else and make the payment through an online challan. For contractual laborers' PF, you must monitor it as the liability and accountability lie with the principal employer even for contractual workers. Keep in mind that PF is calculated based on Basic+DA of that particular month. If a worker is absent throughout the month and has no paid leave, then their salary will be zero, resulting in a PF contribution of zero.
Thank you.