The footnote refers to John Paul II Apostolic Letter, Dies Domini, 31 May 1998. It does not address the administering of First Communion.
I think your copy of Redemptionis Sacramentum has the footnotes mixed up. In the copy I am using, footnote 169 is:
“Cf. Code of Canon Law, can. 914; S. Congregation for the Discipline of the Sacraments, Declaration, Sanctus Pontifex, diei 24 maii 1973: AAS 65 (1973) p. 410; S. Congregation for the Sacraments and Divine Worship and S. Congregation for the Clergy, Letter to the Presidents of the Bishops’ Conferences. Episcoporum, In quibusdam, 31 March 1977: Enchiridion Documentorum Instaurationis Liturgicae, II, pp. 142-144; S. Congregation for the Sacraments and Divine Worship and S. Congregation for the Clergy, Response to dubium, 20 May 1977: AAS 69 (1977) p. 427.”
Footnote 170 is the Dies Domini one.
I am fairly sure that all the documents in footnote 169 are about the need for the Sacrament of Reconciliation before first communion (unless it is just after baptism).
I think the 2004 Instruction Redemptionis Sacramentum is the first document to require that a First Communion be given by a priest in Mass.
In a report on a decree of the Sacred Congregation of the Sacraments, 8 August, 1910, “Quam singulari” at
newadvent.org/cathen/12590b.htm it has under the heading “Abuses following from errors”:
“denying the Viaticum to dying children who had not received their first Communion, and burying these as infants, thereby depriving them of the suffrages of the Church, to which they were entitled (“utterly detestable”, “ordinaries to proceed severely against these”).”
To quote from the decree at
ewtn.com/library/CURIA/CDWFIRST.htm:
“8. The practice of not administering the Viaticum and Extreme Unction to children who have attained the use of reason, and of burying them with the rite used for infants is a most intolerable abuse. The Ordinary should take very severe measures against those who do not give up the practice.”
Does the 2004 Instruction Redemptionis Sacramentum deny “Viaticum Outside Mass” to children who have not made a First Communion in Mass? I doubt it.
It has in n. 87: “Moreover First Communion should always be administered by a Priest and never outside the celebration of Mass.”
Here (perhaps) “First Communion” does not mean “Viaticum”. Code of Canon Law, canon 913 §2 has: “The blessed Eucharist may, however, be administered to children in danger of death if they can distinguish the Body of Christ from ordinary food and receive communion with reverence.” (The Code of Canon Law: New revised English Translation, HarperCollins Liturgical, 1997, ISBN 000599375X.) Redemptionis Sacramentum does not refer to this, as though attempting to change it. I think this canon shows a diffferent standard for a child in danger of death than for a normal child.
The Introduction to the liturgical book “Pastoral Care of the Sick” has “27. All baptized Christians who are able to receive communion are bound to receive viaticum by reason of the precept to receive communion when in danger of death from any cause.” Regarding Anointing of the Sick it has: “12. Sick children are to be annointed if they have sufficient use of reason to be strengthened by this sacrament.” The Code of Canon Law has in Canon 921: “Christ’s faithful who are in danger of death, from whatever cause, are to be strengthened by holy communion as Viaticum.”