Based on the current roster going into training camp and the recent comments of D.J. Smith it looks looks like the primary open roster spot is 3rd line RW.
The RW competing for that open spot are Egor Sokolov, Logan Shaw, Pontus Aberg, Kole Sherwood and Scott Sabourin.
The Sens will likely carry a few extra forwards to start the season so it will be interesting to see who takes those spots. Logan Brown is waiver eligible so that could potentially help him. Ridly Greig will either be playing in the NHL or WHL so he could get his 9 games. Parker Kelly has impressed in the last two training camps and could earn a 4th line or extra forward spot.
Smith likes enforcer type of players so that opens the door for Scott Sabourin and potentially Tyrell Goulbourne to earn an extra forward spot. Sabourin has the inside track with the two way contract and history with Smith but Goulbourne could surprise. Goulbourne is the better defensive forward and defensive play is very important for Smith.
As a summary my early projection for the forwards getting a final look in training camp and potentially cracking the roster are: Egor Sokolov, Kole Sherwood, Ridly Greig, Parker Kelly, Scott Sabourin and Tyrell Goulbourne.
If 2 forwards make the team out of camp and no one else is waived or traded that would leave a roster of 13 forwards. The Sens might carry 14 so maybe 3 from that list will make it.