Ṛkṣā (Riksha) is a Mātṛkā (Matrika; a lesser female deity) who was present as an associate during the abhiṣeka(abhisheka; corronation) of Skanda-Kārtikeya (Kartikeya).

Mahābhārata (Kinjawadekar)(9.46.12)
Mahābhārata Vols. 1-43 (Siddhāntabāgīśa)(9.42.52; see the footnote; vol. 29, p. 476)