Countermark

https://rpc.ashmus.ox.ac.uk/countermark/779 
GIC 654
monogram PHILIP
square 
3.5 - 4 mm 
On obverse. GIC gave PHR as the monogram with Phr(ygia)? Applied at Philippi not certain 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 1656 Show 1656 63 1
RPC I, 1657 Show 1657 21 1
RPC I, 1659 Show 1659 6 1
RPC I, 1656 Show 1656 127 1
RPC I, 1656 Show 1656 89 1
RPC I, 1656 Show 1656 132 1
RPC I, 1656 Show 1656 149 1