Hi, seems it's all with clothes. So no need to worry. If semen on hand has gone in vagina or so, then only u require some precaution. There r few reports of semen on thigh causing pregnancy but it's very rare. For a precaution/prophylaxis , she can take i pill.
Next Steps
from day 2 of next cycle start using oral contraceptive pills or barrier contraception in gorm of condom.