[PPDVBC] question

Hi, Mojo, Pam and I had great fun today and we even placed with points!!!! But, I have a question about how to double for penalty on BBO Our opponents were trying to get out of NT; at the 3rd level, one bid 4H; I passed; the opp’s partner bit 4S; I sats with 5S and was dying to double but the bidding went off before I could…. Can we double for penalty? Thanks, Maria PS, they went down 2, not vuln, and we got our +100 points anyway