A landowner's decision to negotiate a right-of-way agreement with Williams or to instead require Williams to use eminent domain to acquire the right-of-way is their most influential input to the FERC review process.

FERC establishes quite clearly in its published policy statement, Certification of New Interstate Natural Gas Pipeline Facilities, that whether landowners negotiate right-of-way agreements with the pipeline company or instead require the pipeline company to obtain the necessary rights-of-way via eminent domain directly impacts their review process.  This FERC policy is available for review on the FERC website in three parts: PL99-3-000, PL99-3-001, and PL99-3-002 (after considerable background, the policy description begins on page 18 of PL99-3-000).

Consider the following:

The more interests adversely affected or the more adverse impact a project would have on a particular interest, the greater the showing of public benefits from the project required to balance the adverse impact
— PL99-3-000, pg. 26, par. 2
After the applicant makes efforts to minimize the adverse effects, construction projects that would have residual adverse effects would be approved only where the public benefits to be achieved from the project can be found to outweigh the adverse effects.
— PL99-3-000, pg. 23, par. 1
The balancing of interests and benefits that will precede the environmental analysis will largely focus on economic interests such as the property rights of landowners
— PL99-3-000, pg. 27, par. 3
In most cases it will not be possible to acquire all the necessary right-of-way by negotiation. Under this policy, a few holdout landowners cannot veto a project, as feared by some commenters, if the applicant provides support for the benefits of its proposal that justifies the issuance of a certificate and the exercise of the corresponding eminent domain rights. The strength of the benefit showing will need to be proportional to the applicant’s proposed exercise of eminent domain procedures.
— PL99-3-000, pg. 27, par. 2

If you do not record your decision on the docket (click here for instructions), it may be invisible to FERC, particularly if your decision is to require that Williams use eminent domain for your property.  Two years ago, one pipeline company seems to have surprised FERC with the large number of eminent domain proceedings it filed immediately after receiving FERC approval (read about it here).

If you would rather not attach your name to your decision on the docket, you could use the Line List Number for your property that appears on the maps and other documents you have received from Williams, as that will be sufficient for FERC to record and verify the information.  Using your Line List Number is not perfectly anonymous, but as Williams has filed the list of names that match the line list numbers as privileged information (i.e., inaccessible to the public), for most people it would require some digging to make the association.