When I give someone a foot massage, I gently apply pressure to their feet with the warm palms of my hands.
この場合、次のような言い方ができますよ。
ーWhen I give someone a foot massage, I gently apply pressure to their feet with the warm palms of my hands.
「足も身をするとき、温かい掌で優しく圧をかけます」
to give someone a foot massage「人の足をマッサージする」
to apply pressure「圧をかける」
ご参考まで!