Of the doctrine of baptisms, and of laying on of hands, and of resurrection of the dead, and of eternal judgment. (He.6:2) 

And Aaron shall lay both his hands. upon the head of the live goat, and confess over him all the iniquities of the children of Israel, and all their transgressions in all their sins, putting them upon the head of the goat, and shall send him away by the hand of a fit man into the wilderness: (Lev.16:21)

     The imposition of hands in Hebrews 6:2, being one of the "principles of the doctrine of Christ" (v.1) and considered in light of the main theme of the exhortation of the Epistle, cannot refer to a comparatively insignificant NT custom of the ordination of elders and deacons through the laying of hands, or to the passing practice of a visible confirmation of the continuation of the church with the sign of the reception of the Holy Ghost through the laying of hands of the apostles' hands. Those customs / ordinances hardly deserve to be listed among the "principles of the doctrine of Christ". 

     Nay, the apostle has the OT sacrificial ordinances in view which all pointed to Christ. This "laying of priestly hands" upon heads of a spotless, innocent sacrificial animal victim, visibly signified and taught IMPUTATION and TRANSFERRAL of guilt from the people to the lamb / goat, so it should bear the iniquities of Israel upon itself...THIS is one of the "principles of the doctrine of Christ"....