In every such church as aforesaid a portion of the sittings therein, to be determined by the sheriff of the county in which such church is situated, and not exceeding one tenth of the whole sittings, shall be set apart as free seats for all persons frequenting the same; and another portion of the sittings therein, not exceeding one fifth of the whole sittings, shall be let at rent not exceeding a rate to be fixed by the presbytery of the bounds; and the remaining portion of the sittings may be let in such manner as shall be agreed upon by the minister for the time being and the person or persons liable for the repair of the church and for the stipend of the minister, or, in case of not agreeing, then in such manner as shall be determined by the sheriff of the county as aforesaid: Provided always, that one pew shall be appropriated, rent-free for the accommodation of the family of the minister, and another pew for the officiating elders; and the pew or seat rents of any such church as aforesaid may be expended and applied for the purpose of defraying the necessary expences of a precentor, a beadle or kirk officer, and other expences necessarily incurred in dispensing the ordinances of religion therein, and not otherwise provided for, and for the purpose of upholding in due repair and improving the fabric of such church, or of the dwelling house and offices of the minister, or for the relief of any person or persons who may have undertaken or become liable to uphold the same, or who may be liable for the endowment or stipend provided and secured for the minister of such church; and it shall be lawful to make collections at the door of any such church for any of the purposes aforesaid: Provided also, that the sum received by any person liable to uphold the church or dwelling house, or liable for the endowment or stipend as aforesaid, shall not in any year exceed the sum paid or expended by such person in the same year by reason of such liability.