He taught philosophy and later theology at the Chappuy College in Annecy (1680–99); sent to Thonon for missions in the Chablais, for fourteen years he tirelessly preached missions, Lenten sermons, and spiritual exercises for clergy and laity. Superior in Vercelli from 1716, he founded enclosed houses of spiritual exercises in that city and elsewhere. Elected Bishop of Nice in 1727, he visited the entire diocese, which had been without a bishop for twenty years due to disputes between the Savoyard king and the Holy See, held a synod, and built the seminary. He is buried in the church of San Cristoforo in Vercelli. The process for his beatification was initiated in the curias of Vercelli and Nice.
The fruit of his thirty-five years of missions and spiritual exercises in Savoy are the *Sentimens de composition* (Lyon 1709), reprinted many times in French and Italian; *Instructions chrétiennes à l'usage des missions des clercs reg. de St. Paul* (Annecy 1712), in dialogue form; *Retraite spirituelle de dix jours sur les principaux devoirs des chrétiens* (Avignon 1713). Another work in Italian, *Esercizi spirituali fondati sulla suavità della misericordia e il rigore della giustizia di Dio* (ms. in the Roman archive of San Carlo), is highly important because the author collects in one volume all that is currently practiced in spiritual exercises, which “are now the devotion of the public”; it also contains a singular *Meditazione sulla lancia al costato di Gesù* (published by Fr. Manzini in *I Barnabiti*, 14 [1931], supplementary part, pp. 1–6), which places R. among the first promoters of the new devotion to the Sacred Heart.
His major work is the *Ordo Amoris seu theologia ethico-theorica ex maximo et primo dilectionis mandato nova methodo disposita*, 2 vols. (Milan 1719 and 1722), a summa of dogmatic and moral theology in which the entire construction is fervently mystical, centered on Love: from assisting love in the treatise *De Gratia*, to the disorder of love in *De peccatis*, to the various healing aspects of love in *De Sacramentis*, and so on, culminating in the ordering of all other loves in *De Charitate*, the *De uno et trino Amoris obiecto* in *De Trinitate*, the *De primis dilectoribus Dei* in *De Angelis*, the *De Magistro et pignore Amoris* in *De Verbo incarnato*, the *De Amore reddente unicuique suum* in *De Justitia*, and finally the “Reward of Divine Love” in *De beatitudine*.