'In remembrance of me' can then scarcely mean 'that you may remember me', but most probably 'that God may remember me'. This means that the command to repeat the rite is not a summons to the disciples to preserve the memory of Jesus and be vigilant ('repeat the breaking of bread so that you may not forget me'), but it is an eschatologically oriented instruction: 'Keep joining yourselves together as the redeemed community by the table rite, that in this way God may be daily implored to bring about the consummation in the parousia.' By coming together daily for table fellowship in the short period of time before the parousia and by confessing in this way Jesus as their Lord, the disciples represent the initiated salvation work before God and they pray for its consummation.The Eucharistic Words of Jesus, 254-255.
According to the Reformed, the sacramental union is a spiritual bond, effected by God the Holy Spirit, and received by faith, so that by receiving the sign (bread, water, wine), the thing signified is also received (the promises of the covenant, the forgiveness of sins and participation in the resurrection life of Christ).http://www.christreformed.org/lecture-5a/
According to the Scriptures, sacraments contain an outward or visible element. That is, sacraments are based upon material objects: water in baptism, bread and wine in the Supper. But a sacrament not only includes the material element prescribed in Scripture, but this also extends to the rite itself as commanded by Scripture. As we have seen, this language is used in connection with the Covenant made with Noah (Genesis 9:12-13), the covenant made with Abraham (Genesis 17:11); and as confirmed by Paul (Romans 4:11).http://www.christreformed.org/lecture-5a/