Corollary
Tag 09DV, permanent. Cite it as [Bourbaki, Tag 09DV].
Integration, chapter VII, § 1. Construction of a Haar measure
— The topology of a nondiscrete locally compact field admits a countable base.
For, K is the union of compact sets . On the other hand, K is metrizable by Prop. 1 of GT, IX, §3, No. 1. Therefore the topology of K admits a countable base (loc. cit., §2, No. 9, Cor. of Prop. 16).
Bourbaki puts the proof directly after the statement, so what is above is the statement and its proof together.