The new RCA siddur has not been released yet even though they announced (on their website) its publishing 5 years ago!
I contacted the RCA and they didn't respond.
The RCA has announced that it will be released in March of 2018. It is a partnership with Koren Publishers Jerusalem.
https://www.makorrishon.co.il/news/10159/ article about the siddur.
UPDATE
The updated information shows that it will be released August 1, 2018.
Siddur Avodat HaLev
The NEW RCA Siddur - Siddur Avodat HaLev is a full siddur for Weekdays, Shabbat and Haggim.
Five years in the making, this outstanding Siddur from the Rabbaim of the Rabbinical Council of America features:
Fully Contemporary translation
New commentaries utilizing classic as well as contemporary Rabbinic and traditional sources
Additional prayers for life-cycle events and the modern observance of Yom Ha'atzmaut and Yom HaShoah Yom Yerushalayim
Complete Sefer Tehilim
Supplementary essays by classic and contemporary Rabbis
Appropriate female textual and grammatical formulations where needed
Rabbi Basil Herring, Editor in Chief, in conjunction with other outstanding Rabbaim of the RCA
The Siddur Avodat Halev is the new standard Siddur for RCA Synagogues for generations!
For Bulk orders, please contact [email protected]
PREORDERS ONLY - Orders will not be processed until after August 1, 2018
$34.95
ISBN 9789653019362 Size Standard Language Hebrew/English Binding Hardcover Nusah Ashkenaz