In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
Once the head of the penis enters the private parts of your partner the fast is broken and Qada and Kafara become Wajib irrespective whether or not ejaculation takes place. (Bahishti Zewar – Maulana Ashraf Ali Thanwi (RA); Vol.1; pg. 337).
The Kafara for breaking the fast of Ramadan is to fast for 60 consecutive days. If one is unable to keep the fasts then he should feed a needy person, two full meals per days for a period of 60 days. In lieu of the actual 2 meals per day one may elect to give the equivalent value in cash. It is sufficient to feed 60 needy persons two full meals in one day or to give its equivalent in cash or kind. The equivalency in cash or kind is the value of sadaqatul fitr. (Bahishti Zewar – Maulana Ashraf Ali Thanwi (RA); Vol.1; pg. 342-343).
You should make sincere Taubah to Almighty Allah for your mistake and make a firm intention not to repeat the mistake.
And Allah Ta’āla Knows Best
Mufti Saeed Ahmed Golaub
Islamic Solutions
Jamaica